This change will be slower, but it seems a truth that in life, inside a company and in communities, there are some people who do much more work / have more influence than others. If the best / brightest / most helpful etc people leave, there's rarely much more than a shell left.
I think the Fediverse will slowly pick up steam, and perhaps rival reddit in 5 or 10 years. Which is fine. One long-term advantage of the Fediverse is that it's more immune to corporate shenanigans. And ultimately, for all of us, this is a long game.