I'm pretty intrigued by all of that.
I actually loved Damnation, as an example, far more than Deliverance. I just thought the song-writing was more interesting on Damnation. And that, in the end, is all I care about with Opeth. If they deliver good song-writing, it will be awesome no matter what style they choose.
Katatonia hasn't done DM vocals in years and that band turned out pretty damn okay, right? I don't see this as the end of the world in the least bit.
Besides, there's always Bloodbath anyway...good enough for me.