Metal just needs another formative era like we saw in the early to mid eighties where genre lines were a bit blurred and the music was MUSIC first and a genre second. A lot of bands these days fall into one of two traps. They either get stuck in the confines of a genre and keep rehashing time tested formulas and ideas, or they try too hard to mix genre's together. Not enough time and effort is taken towards the spirit side of the music these days either. Take a look at early Bathory, musically it took the hardcore punk structures of GBH, put them into larger frameworks, used unconventional harsh vocals, and spoke of darker more romantic fantasies, all while retaining a youthful playfulness. Something like this is needed today, just building off of all the great concepts metal has already accomplished. The main thing is metalheads need to get a bit more serious about actually composing pieces of art instead of trendy riff salads. As with all things, a holistic view of the situation is needed.
In the end the form of the music doesn't matter as much as how it's composed and what it communicates. As far as forging the basic framework of a sound, the current generation is very lucky in that they can look to the past and see what works and what doesn't, and how to use certain techniques to accomplish specific goals. The future of metal is in the hands of the Hessians who know and love this music and need to step up and create more of it without falling into the traps they've seen their predecessors become ensnared by.
As far as punk, it is dead and does not need to be resurrected. It served as a catalyst, and has no future. Really it shouldn't be seen as a genre but as a philosophy and a movement that can be applied to multiple situations. View it as an active nihilist views a state of utter nihilism: a tool. We should be punk, in that we should make use of a DIY ethic. We should be punk in that we should value simplicity. We should be punk in that we should be aggressive and feral. But we should not be what punk has become, a stereotyped fad. We should not be punk as in favor of populist rebellion.