I wanted to edit my post, but I kept getting the gateway error, and it only let me post now
For me having additional companions offer to turn into mind flayers would not help their story (in this case Wyll's), because it would just be another bandaid on bad storytelling. I don't think Larian is going to rewrite the main story anyway.
So I'd rather they improve Wyll's storyline, like: have him make the big choice, let the player kick Mizora out of camp (for example by having Aylin smite her into pieces), make his final quest more about him.
