Here's my prediction, but I'd like others to contribute their predictions as well. I think it's important that we make ourselves aware of signs before they start showing, and that we have a record to point to if things play out exactly as we predict.
- Threads launches, federates with the 'verse, everything works well and actually seems hunky-dory. Even companies/restaurants/officials that use a Facebook page might be accessible via federation!
- Threads starts allowing their users to embed and interact with content from Facebook, Instagram, & possibly WhatsApp using Threads. Federated communities will be able to embed some of that content as well. Also, InstaWhatsBook users will be able to link to Threads posts as well.
- Sooner or later, embedded content from the Meta's 'verse will encourage and eventually require you to be signed into Meta. This will be for the "security" and "privacy" of Meta users. But don't worry, you'll simply be able to link your federated instance's account to a Meta account real easy, and even keep your credentials & karma status synced as well!
- Eventually posts from Threads users will be restricted even further and you'll have to visit their site in order to "securely" view that content. Don't worry though, you synced your account before so it's not really an issue to just hop over.
- People get tired of having to hop over to Threads for most posts, and since their credentials are synced to both, it doesn't really hurt to just stay on Threads and view federated posts from there.
- Meta changes the nature of their karma system so not everything syncs anymore. Of course you get the most benefit if you're posting on Threads.
- Meta finally decides that federating "just isn't in their best interest" and shuts down federation, leaving a husk of the Fediverse behind.
Meta already is already 5/6 of the things you listed out there. Threads is the microblogging product, but Meta is the platform.
They don't need to destroy every single piece of competition in EEE. That happens much more passively.
They just need to make the others slightly worse to use. A bit at a time. Until a significant decline happens. Until enough users are annoyed about their "green bubbles" or whatever so as to make the switch. To culturally enforce the superiority of their product over others. If you understand the EE part, then you must understand the inevitability of the third. When was the last time you logged into IRC or ICQ? For most people, the answer is "What's that?" because XMPP and the interoperable protocols in its halo were extinguished. Google Talk and the like joining the arena looked like they would make the sphere better, but instead killed it.
Meta is a publicly-traded company in a capital market. The way they will behave -- selfishly and without care of the treatment of their users and customers -- is preordained. Their motivations are necessarily corrupt and you need to defend against that.
Meta stands to gain very, very little from maintaining a vibrant and healthy greater fediverse space. It doesn't need to deliberately intend to harm federation, it just needs to exist with all its power and money and be selfish while doing it.
Ultimately, I don't know that federation with Meta is damnation for the fediverse. But the risk seems too great to me.