From what I've heard the reaction is split. Some people want to federate as much as possible, other people are arguing that meta will screw over the fediverse (and I agree with the second group)

There's also some pact thing, fedipact if I recall correctly, to defederate from meta if it tries to join the fediverse

I imagine some will try to federate with Meta and hope for the best. Some other admins will immediately block those instances, while the rest may take a wait-and-see approach and then start blocking them the moment Meta is caught trashing users.

I'm generally pretty anti-corporation, but federating and working with corporations is a great opportunity for the Fediverse. Corpos like Twitter, reddit, and meta would provide an easily accessible path to be in the Fediverse for non experienced users. And the Fediverse in return gets more users + more content etc.

You essentially get the opportunity to keep your data out of the hands of corporations(pseudo anonymously + open source) while being supplied with content from the average users.