This will bring some more potential users who, without threads, would never know that fediverse existed. Then they will surely start adding features that mastadon/lemmy/etc don't have and it will be the time to pull the plug and defederate them.

Highly doubt that it will bring any harm to mastadon, for example, simply because their userbase does not care about meta crap, but in exchange it will get them some users for free for sure.