Exactly! A metal band with no drums wouldsound shit! As a drummer myself, I am am naturally going to argue the case for drummers though!
Fair points about keeping the beats and things like that, but that doesn't mean metal drumming has to be as straightforward as a fast 4/4 rock beat. There is a lot more to being a drummer than just keeping the song in time, although that is an important aspect. Someone said that the guitarist could just keep the whole thing in time by counting in his head, but I can't see that working. You need a solid presence to hold the band together - the drummer.
The interest of metal drumming is only limited by the creativity of the drummer, so as long as there are still talented and visionary drummerds around, I can't see them becoming obsolete in metal! The drums are easily as important as all the other instruments in a band!
You could say the same about bass players - this isn't to bash at them necessarily, just to point out that if what you say is true, then bassists should also become obsolete, because they're only there ro hold the band together and provide a solid foundation for the rest of the band - again, wrong. Each instrument is only as boring as the person playing it!