I’d love to see Taika Waititi take the reigns for Vol. 3. I feel his style would mesh really well with the tone of the GOTG movies.
Ehh I keep hearing people suggest this but I disagree. Ragnarok and GOTG are tonally similar in a broad sense, but ultimately Waititi’s voice is quite distinct from Gunn’s, and I’d really just prefer him to do the next Thor if anything.
As for Vol. 3 without Gunn, I’m not going to worry too much yet. While it’s a shame he won’t be able to round out his trilogy (though honestly IW already kinda hurt it’s cohesiveness anyway), more likely than not they’ll still be working off his script to some extent. Depending on who they hire as a replacement, it could end up being just fine.