The beehaw and world defederation (which I assume you are referencing) is temporary because beehaw believes the increased traffic cannot be moderated without proper mod tools.
And while you’re right about mainstream things like gaming or technology won’t have a single main community, I feel more niche communities will be able to setup their main communities. Obviouly that’s just my opinion, but there are some signs of that happening already. (c/piracy for example)
Password managers are as important as adblockers in this day and age imo