I certainly hope so; I’m on Wolrd, and most of my favorite communities are located on World, but I often find the admins’ decision questionable, and I have just as many reservations about ml. I hope I could put together a good group of communities without either instance, but sometimes it feels like they’re necessary to a good Lemmy experience. But either way, I think you’re right, most instances won’t defederate.
Sooner or later, you will get trapped somewhere forever. Over the course of an infinite lifespan, the odds that a building collapses on you or a tunnel caves in on you basically become 100%. Someday, you will fall into the hole that you will stay in until the sun explodes, and then you will drift in the void until the heat death of the universe.