You bring up a very good point. Currently lemmy.ml has thousands of users. Lemmy.world has thousands of users. The hardware they have selected to run their instances is adequate for now, but, what is the plan for scaling out if the user base grows? Is there one? They have a donation page on each lemmy instance (click or tap the heart icon,) but that can’t be enough to pay for the cost of running something used by millions of people, even if only 100s of thousands are ever only online at any given time.
In terms of UI/UX, @[email protected] has mentioned in a post they are currently working on major performance improvements and enhancements.
Ideally, yes. If that can be the reality, and I suppose that is how it should would with federation, then server costs should never get out of hand.