One potential outcome I can see is that the mainstream channels suffer from a kind of "Gresham's Law" - bad speech drives out the good. If you have something to sell, or you want to swing an election, you're on Facebook/Twitter. Whereas the genuine conversations are happening on Discord/Mastodon/etc.
I think we're already starting to see this happen (Twitter is full of brands, influencers, politicians, etc.), but it's happening slowly.