For instance, the Mastodon project and mastodon.social are run by a non-profit. They have their own mastodon account which discusses updates, advertises merchandise to support them, and could ask for sponsors or donations if needed. Users can subscribe to their feed if they want, and support them should they need help, while users who don't want advertisements won't be affected. I'm confident in the stability of this model for them so I chose to make my Mastodon account on their instance so I can trust I won't have to transfer to another someday should one shut down.

I'm hoping the digital space evolves in this direction and that we approach a post-advertisement economy.

Otherwise, enshittification keeps ruining things and we can't rely on the long-term stability of anything. Just look at Google.

> they could someday stop updates to these apps too to replace them with another monetization scheme

The code is still being written and kindly released under the terms of an open source license, so if that happens, I'd expect that sufficiently motivated people moved by strong needs or ideals would be able to fork it and keep using (and possibly even improving) them without issue, as the license explicitly allows for it.