- A way to backup your whole user data and completely restore it on any instance you want. If an instance goes under, it should be possible to keep all subscriptions, all your posts, all your comments, and migrate them to a new instance.
This would be great.. also even if the "restore" part were not possible (yet?) I feel offering a way to extract your data might even be a requirement for a server to be fully GDPR compliant (though I could be wrong on that, IANAL), reddit does allow you to download your data after all.
It does not have to be something mandatory...
I mean, there could be some form of "metacommunities", something like being able to group multiple communities together in a "view" that shows them to you visually as if they were a single community despite being separated. Bonus points if everyone can make their own custom groupings (but others can subscribe to them.. so there can be some community-managed groupings).
In theory you could have multiple "metacommunities" for the same topic still.. but at least they could be sharing the same posts if they share communities. I feel grouping like this would be helpful because small communities feel even smaller when they are split.
I think reddit has something similar to that, multireddits or something I think they are called.