IMO the success of BlueSky is good for the Fedi. It can take the “let’s be the next mainstream thing” monkey off of its back and just be itself.
Plus, it keeps the obnoxious “But muh follower count” fame whores and the majority of the “Why can’t this be exactly like Twitter, I want a total Twitter clone” dumb-dumbs out. They’d ruin Fediverse culture even more than the second migration wave two years ago which was so massive that those who fled back then only encountered each other on Mastodon and hardly anyone who had been in the Fediverse before then.