It actually would be a good thing. Pariah instances are how the fediverse will have to moderate itself, and these people have shown themselves to be incapable of playing well with others. I purposely avoided joining any of their subs because I saw how toxic their influence was on reddit.
If you look at peertube, there's one instance that hosts Steven Crowder and Alex Jones and like two other people who I assume are lesser demons of some kind. I would avoid any instance that doesn't have the good sense to defederate from that one. This is a similar thing. I doubt the tankies are going to be on the popular side of the schism if it happens, they would have an echo chamber and we would be rid of them.
The thing about an echo chamber like that is that thanks to the public nature of federation status, it would be obvious who the pariah instances are, so anyone still there would be made aware that they are the minority, not the voice of the people in any way. That's something that takes longer to notice in a forum like truth social. The numbers might be there for people to see, but it's a different platform so you can say there's a slow adoption rate or something, like you can say about Lemmy. With pariah instances there is a direct and obvious comparison, and people have left because your instance fucked up. That's going to drive all but the most hardcore folks away to other instances.