It sounds like you get it but what I'm saying is you just add colo'd (or whatever) peers. Nobody in particular needs to be responsible for that. Bandwidth in Eastern Europe, for example, is dirt cheap - practically free. It'd be similar to how we do Mastodon: a bunch of different peer networks with a bunch of different funding and management models. You don't need to rely on the instance server for hosting, just initial seeding. Think of it like the original seeder in BitTorrent (a model which we see working great to this day because people rent dirt cheap seedboxes.)