Every western alternative to YT failed so far and things like p2p are obviously not anywhere near viable.

If there is ever a non-western alternative like Tiktok, well its obvious it wont be allowed. So realy there is very little reason to be optimistic about this.

If YT dies it will be because people moved on to some other entertainment form, maybe VR will be the big thing in 2060 and people will laugh at us idiots wasting time watching "non interactive media" just like we laugh at newspapers and radio. Maybe the "AI" nonsense will actualy deliver something remotely useful for making videos on-demand or something, though that is just cringe and silly it may happen...

So unless that is where we're heading I think sadly YT will be here to stay for at least a another 10-20 years.

To be honest in the medium-long term I'd bet on climate change making energy prohibitive and therefore killing most of current social media server capacity than anything else.