I'm sort of ok with cosmetics only mtx, which was again
confirmed by the GM of the Diablo franchise, but I just hope it's nothing too overwhelming for the content that's already there. And ideally, I also hope there's a path to obtaining that content without paying, even if it does takes grinding or doing some feats of skill or strength.
I'm pretty sold on Diablo 4, and another thing I hope for is that you can control how much of the world is shared with other people. From the little I played of Diablo Immortal, that was the main annoying thing, having players keep drawing my attention.