One of the bigger tragedies in metal is Akerfeldt not just singing with a normal hard rock heavy metal band, he's got a great voice.
I think he should do more work with Steven Wilson like the album from Storm Corrosion but do more prog that isn't on the death metal side of it. That way Opeth fans win if they want the death/black metal vocals in it and people who hate those vocals can still get plenty from his clean vocal talent.