I think the fundamental question is, as the Fediverse gets more popular, then how will servers get paid for? Here are some possibilities I see for how Fediverse hosting could work at scale:
Surviving off donations alone: Possible but in my estimation unlikely, and it could veer into the territory of big donors having a controlling stake or exerting their interests.
Instances limiting number of users to what they can afford: This would require the network of instances process to really work well.
Big instances selling advertisements: Without oversight or moral commitment, this could easily go towards creepy personal data collection.
Crowdsourcing the costs: This would require transparency and fundraising or some other model
Hosts financing the operation in other ways: This could also easily get into creepy data collection practices or other dark patterns.
I hope we come up with some process or plan for avoiding the pitfalls and forging an honest and community-integrating way forward.