Some bands have such a distinctive sound, and an ability to be instantly identified from this trademark, that for them, trying to do anything different is not just difficult, it's impossible.
Audioslave would have to remove parts of the whole in order to shift that whole away from itself. Chris Cornell's unique, beautiful gift of a voice will always be what it is, and Tom Morello's guitar riffery will continue to remain as identifiable as ever.
Given these constraints borne out of talent, can Audioslave manage to create product that sounds different enough from previous material to make it worth the investment?
Sadly the answer would have to be no. Revelations is Audioslave by numbers, a sure sign of a band that reached their creative pinnacle and managed to stay there through sheer strength. Don't misunderstand though, this is not poor quality, badly written music. It's well crafted, imaginative and effortlessly voiced by an angel, just as Audioslave always managed to achieve.
It's not hard to imagine that in 46 million years, when the Earth is awakening from its 47th Ice Age, and a new species of half human, half robots walk the planet, Audioslave will still be releasing quality albums. You'll still only need to own the first one though.