My predictions about threads:

FaceBook will fail to receive enough control over fediverse for time being, thanks to publicity their issues was given. They will probably be federated with some new instances, especially corporate-driven ones.

The thing they will or federating with mastodon social is good for reason you can contact person from threads by creating an account on mastosoc. It should only be used if you MUST interact with someone at a proprietary network and Threads is an option. Otherwise ask to make mastodon account