To be honest, bluesky will become the left version of "Truth social". That's good for them in the long run (ad money) but it'll be another echo chamber. I follow both left-leaning and right-leaning people on Twitter and I don't see the "balance" going one way or another.
The other thing is reach. Twitter, Fb, Instagram are global brands. It'll be really, and I mean difficult to move the rest of the world to other platforms (TikTok is the exception because they went ahead with video from the get-go).