Adding on to the pile here:

I know many have said, but embrace, extend, extinguish is also a legitimate threat to the fediverse I feel. I think the scenario you’ve described is already happening, but it’s natural compliment: Unless you pay the google/godaddy/squarespace/whomever racket, good luck getting any traffic from your personal, self-hosted email server. Even if it’s fully signed from industry standard certificate providers, you still need to effectively pay the big email servers to have your traffic be not marked as defacto spam/malicious. If you run the show, you get to point the protocol and standard operating procedures. Meta has every capability to eat the fediverse more or less, and frankly I don’t doubt they will if it is a profitable endeavor. I’m sure y’all have read this by Ploum, but it really articulates the genuine concern that is just as existential as implosion.