I disagree. Bands don't typically put 12 years between releases and come out with a quality disc in the end. In all likelihood, new material will only serve to taint their legacy.In my opinion, AiC could easily go forward with him on vocals, and it would be a shame if they didn't record some new material.
I haven't heard Duvall sing, so I can't comment on the Scott/Johnson - Staley/Duvall analogy. However, Scott and Johnson were completely different singers. From what I've heard about Duvall, he isn't all that distinct from Staley.AiC would never reach the commercial heights of AC/DC, but I think they have their Brian Johnson in William Duvall.
If Staley, Duvall and crew want to put out new material so badly, and it isnt about fattening their respective retirement funds, than why put the Alice in Chains tag on it?
Zod