This is all conjecture, but:

• The Platform Formerly Known as Twitter will get forgotten. Threads will get some momentum and then people will forget about it. Mastodon will likely grow, but it'll never grow to the same size as Twitter.
• Reddit will also go kaboom. Most users will go to Discord, a sizeable minority will come to Lemmy, old style forums will see a small comeback. As the above, Lemmy will also grow, but not to the point that it becomes as huge as Reddit.
• Depending on how the Kbin side of the fediverse plays its cards, it might go huge or it might get a small growth. It has the potential to attract users from both Twitter+Threats and Reddit.
• Facebook will get worse. To the point that not even your grandma will want to browse it. Eventually Meta will decide to cut off the losses and divert resources to other enterprises (specially WhatsApp and Instagram), making it even worse. I don't think that it'll last 10y. I think that this model of social network won't get a good replacement.
• Instagram might get some losses, but nowhere as bad as FB. PixelFed will see a modest growth.
• Discord will get huge regardless of enshittification, and this is what will promote the beginning of some activitypub alternative to it.
• Some Wikia-like activitypub platform will pop up. Initially "attached" to other services (mostly Lemmy and Kbin), but eventually dwarfing them. The relationship will be mostly symbiotic though.
• YouTube will stay. As shitty as possible. Google is not dumb, YT is one of its cash cows and they'll tweak YT to be as annoying/advertising/shitty as still bearable by its users.

So overall I think that the fediverse will get huge, but none of the underlying platforms will. The main strength will be how they connect to each other.

"In a last attempt to stay relevant, Spez added a new feature to Reddit, which automatically converts every comment into an NFT, that you can sell for real money transactions. The author's name will change to the NFT owners."

"Meta changing it's name again, to ZombiOS, after releasing it's desktop OS, based on iOS with Facebook integration."

"Lemmy user number raised the 10th time year to year."

"After Elon Musk shut off X in 2024, he decided to go for a comeback. To honor the name X, he let his son X$alaπ¢ work as CEO of the new Y website, targeting neuralink social Media, where you can share memories directly into the brain."

Random thoughts ...

If ActivityPub makes it into being a big deal in the future, I'd suspect some new stage of growth or development would be necessary. Either something gets added to the protocol or the architecture of the fediverse develops into a more sophisticated set of interacting services or the software ecosystem actually matures into an ecosystem. Without any of that I'd predict it stays relatively niche.

Should a decentralised protocol actually make it big, it could be game changing. But my "shot from the hip" bet right now is that ActivityPub and the current fediverse ecosystem is not it.

Apart from that, I'm actually thinking nothing terribly dramatic happens. There'll be some fracturing, but in the big picture it will remain relatively fringe with the core platforms remaining mostly in tact with large user bases.

If there's any real tectonic shift, I'd say that the 2010s idea of social media is on its way out (which is part of the reason why I'm not betting on the fedi going mainstream, as it's mostly stuck in the past). I think a big divide breaking now and into the short term future is that between private "true community" interactions such as in private group chats or on discord etc and public high-utility or high-entertainment content such as youtube, tiktok, wikis and maybe twitter going forward. Private chats will be where you have your network and the public domain will be where you extract value, with AI/algorithmic assistance playing an increasing role, or attempt to become a creator. Another reason why I'd bet against the fedi is that it tries to walk what I suspect is an awkward middle ground between private and public spaces without actually providing either.

How the great AI-ification affects things, I'm not sure. I'd bet it basically pushes social media into a winter of sorts, with the platforms that exist becoming more closed off (see Reddit API stuff) and the value of genuine human-only spaces going up (see private + public comments above).

Amongst all of that, I'd suspect that the platforms themselves won't really matter as much any more. You'll get whatever you're looking for wherever it's available from which ever service or creator is providing it, but it won't be a pleasant experience getting it and you'll feel generally bitter and frustrated by the experience. Meanwhile, you'll have whatever app(s) you need to stay in contact with those that actually matter to you, which again will depend on who's using what, not what you chose to use. Otherwise, everyone and everything you interact with will just be an ephemeral and confusing and increasingly detached internet blip.

How would monetisation work on a decentralized platform? Would the creator be limited with merchandise and promotions without ads?

The patreon / liberapay model is the future.

Same as it currently is. Maybe some will fade to irrelevance but a new company promising to be everything the other one wasn't for free will appear and the cycle will continue. The focus will go away from user choice and further towards algorithm driven short form content. I could totally see an app that just shows you a 3 second video, then another, then another continuously until you close the app. No input required as the engagement is tracked through the camera.

The metaverse is supposed to take off eventually as young kids start using it.

How would monetisation work on a decentralized platform? Would the creator be limited with merchandise and promotions without ads?

We went over a related business case in my MBA just yesterday. You can look at what Adidas did: they partnered with the Bored Yacht Ape Club to produce NFTs that ended up selling for $22 million. That marketing strategy hinges on working with recognizable folks that are already established within decentralized areas. And that's what it's probably going to be about, at least at first: building relationships rather than direct monetization. It'll actually be really nice, probably.

Except that's how all internet platforms start. Then it'll be enshittified. You know what enshittification is...but if you don't:

it is a seemingly inevitable consequence arising from the combination of the ease of changing how a platform allocates value, combined with the nature of a "two sided market," where a platform sits between buyers and sellers, holding each hostage to the other, raking off an ever-larger share of the value that passes between them.

So, I predict over the next 5/10 years, as the metaverse gets set up and whatnot, social media might become slightly less shitty for some time in there if you're willing to engage on these decentralized metaverse platforms. Because you know damn well that Reddit and TikTok are going become thoroughly eshittified until all the value is extracted from them, and users will have to look for alternatives.

Most corporate social media companies convert to a system of content creators that earn a living off their work, either as direct compensation from the company or via embedded ads. Non-professional participation is usually through this lens.

To keep users on the system, private networks are developed and expanded. Private chats and discords develop to full on forums.

Federated networks are out there, but it isn't the default. A lot of it is based on specific fandoms. Likely, this is funded with donations, which starts being problematic as communities become dependent on a set of benefactors.

Corporations will find a way to ruin decentralised platforms and we'll have to find something else to use

Big tech companies run out of new users to exploit and they end up collapsing (since in a capitalistic model you either grow or you're doomed). With these companies going down, all the internet infrastructure goes down, unable to fight simultaneously the power shortages due to unavailable resources and the continuous strike of workers who cannot afford a livable wage anymore and civil wars in a world where natural disasters are more and more frequent.
With the internet down the society as we know collapses.
Now social media is people telling stories around a campfire.
Those who say dumb mean shit get slapped hard in the face.
Humankind's healing process begins.

Same for any content. If successful, it will attract investors. Sell the site to these investors. Use site to sell stuff to captivated audience. Monetize every inch of space.

All these websites need attention. Once they have x amount of eyeballs they get sold. The 'we're just cool guys building a website' only lasts until the money starts being offered.

I'm certain that some activitypub implementations will be normal with some normies (governments/ universities creating their own socials), but also certain there wasn't be one implementation that all normies are using.

In the same vein I think there will be a greater portion of users who are active on many platforms. 5 years ago most people engaged with content on a single chosen platform. In 5 years most people with engage with many platforms.

I think the common theme amongst all platforms will be a desire to control the content we see.

In ten years we'll have virtual rooms that we can explore with VR headsets. No matter which platform, they'll all be connected, but who sells the best headsets will matter.

One thing to consider is AI is going to make getting set up and using things like activitypub much easier - especially as it'll be making it much easier for Devs and users to customise tools to basically break out of the social media boxes, your ai will be checking your social media accounts on a range of platforms and keeping upto date with where creators you like are posting so it'll show you interesting stuff no matter what platform it comes from.

I think by being the most open and flexible we'll see a lot of growth and development here