Lets see what the future brings. As long as the user count is low there isn't much of a problem, but if instances suddenly have millions of users, it will get expensive for admins to run the service. If too few people donate (what is usually the case), admins are forced to search for other ways to finance the infrastructure.
The other point is AI, wheter you like it or not, if Lemmy is big enough, the content (conversations etc.) will be used to train LLMs. Also, the content will certainly be interesting for advertisers to learn user preferences.
The difficulty comes with scale.
Why not load balance all content to all instances? So if an instance gets killed, the content remains. Or at least a backup strategy to rebuild an instance in the event of a take down
People stay if there is enough content and the user experience doesn't suck. So fare, more and more people try to engage and build new communities. Just try to add value. Also the UI and Apps improved quickly but its fare from perfect :-)
back to the roots I guess ¯\_(ツ)_/¯
Who needs fancy GIFs anyway (╥﹏╥)