Wow the Mastodon FAQ on Meta is a piece of work. Really short-sighted and apolitical.
"Will Meta embrace-extend-extinguish the ActivityPub protocol?"
1. Yes.
2. 'No, look at XMPP, that is still around' is the worst argument. XMPP is completely harmless and neutered with respect to challenging platform power. There are great people working on it and I use it daily for many years, but from a political perspective it is dead. It improves but is steadily years behind the curve with features. Momentum and perspective matter! It could have been turned around if an easy integration with Mastodon was made as it would have given Mastodon instances e2ee messaging, but that didn't happen. (Not too late for that yet btw!)
3. Here is how Meta will EEE ActivityPub:
It will start with Meta being the first ones that ship full account portability including post history. That is hard problem to solve decentralized, which is why we have it yet. But Meta won't care about that. They will just use Meta nameservers as a centralized identity provider which will make it possible. (Similar to how Bluesky does it btw. ) They are extremely well positioned to do this, FB is already "the identity platform" and there is regulatory pressure. From there on there will be increasing incompatibility and extensions on Meta's terms.
"Will Meta be able to show me ads?"
What prevents someone from liking or boosting sponsored posts from a generic sugary beverage company and that showing up in your timeline? It is a sad fact but true: people actually "like" and share ads.
Even then, what prevents Meta from sending out ads in your friends name the way they do on their own platforms? X like this, so now we show it to you as well!