And that’s certainly something I’m worried about. If the admin of programming-dev gets tired of running the instance, it could just disappear.

And I’m happy with using servers as an optimization, but IMO it should always allow users to host at least a portion of it themselves without a server. As in, everybody becomes a seeder. That way, if an instance gets hammered with a DDOS or something, the network can still survive by routing around it.