I think metal needs to look at its history (and the ancestral history of its adherants)for traces of conceptual elements that can be woven togethor into a whole to which future music can unify itself around. For example, whether you agree with its outlook or not, 'punk' as a concept rather than just one particular genre of 3 chord rock, is very diverse (i.e. punk, new wave, hardcore, crust, post-punk etc.) The unifying concept in this case seems to be one born out of the larger post-modern movement: a generally egalitarian individualist stance against society and its aesthetic judgements of what is 'good'. That attitude expressed itself in a myriad ways for better or worse. . Metal needs to adopt this same approach as it will find itself more musical freedom but still keeping a distinctivly 'metal' attitude that trenscends simple descriptions like 'brootal' or 'raw'. When metal starts progressing again,the innovations will not be novelty but meaningful ways to express content.
Speaking for myself, the stuff I write is somewhat ambient but also has this strangely intimate feeling as if it was played on a classical guitar.