"We've got this new awesome feature, and we asked nicely if it could be put into the ActivityPub docs but they turned us down/didn't act fast enough. So we're proud to announce MetaPub, a superset of ActivityPub that will still communicate with regular ActivityPub, but to get the best and latest features you'll have to implement MetaPub in your clients. Or just use Threads, where it's already present for all users!" Repeat until you gain enough influence that ActivityPub is seen as inferior.
Then comes "Extinguish." Breaking changes to MetaPub reducing federation to only MetaPub clients or give up entirely and turn off federation anyways.
ActivityPub is the first glimpse at a future where social media networks are interoperable over a common standard similar to mail. And from recent history the period we are in is one in where governments are looking for open standards as a hedge against big tech.
The idea that Meta would deliberately harm a standard, shut down competition and invite anti-competition investigations is far-fetched.
And then we revert to the state where we don't federate with threads, which doesn't seem so different from not federating with them today. This is weird jealous break up logic. No, you didn't stop talking to me, I stopped talking to you!
At the same time, Meta cannot stop non-Threads instances from organizing as they already do.
So I don't see the threat, really.