Here's a thesis I'm working on: Second wave black metal (early-mid 1990s) and war metal (Blasphemy's debut was 1990) are two responses to the same event - first wave black metal. Two things follow: both are "true" to black metal in a certain sense (though I think at this point war metal's fidelity to black metal is unable to produce much newness while still remaining distinct as war metal); both are fairly separate lineages (war metal is not a simple subspecies of black metal, but an alternate history, black metal's alter-ego, a different response to, say, Bathory).
Seriously, listen to something like Blasphemy's Fallen Angel of Doom... Conqueror's War Cult Supremacy and then listen to any album in the second wave. Totally different, no joke. It's about melody and lack thereof, it's about aesthetic, it's about atmosphere, and most importantly (I think) it's about negation. Second wave black metal was negative, but still had room to grow. War metal is so damn negative it negates everything that's not itself, including its possible future growth, what it could become. War metal is ideologically and musically restricted by its fidelity to what it thinks is "true" black metal. This negativity is articulated on every level - imagery, musicianship, production values, even distinct instruments and notes. It attempts to negate everything about western music - black metal as the coming of the musical/ideological antichrist. These things always go together in war metal. It is one of the most ideologically and musically restricted microgenres I've ever heard.
This is not to say there isn't good war metal. I would not be so insane as to claim war metal was always saturated, that it was always the bad counterpart to the second wave's good. Actually, quite the contrary - I think I like Blasphemy, Conqueror, Revenge, and Archgoat more than most second wave bands. But in all honesty, I think most bands labeled war metal are bad imitations. Strictly speaking, there was one bestial black metal band, Blasphemy, and one or two war metal bands, Conqueror (definitely) and Revenge (most probably). If I had to canonize, to define the definer of these styles (which for now I'm holding apart), those would be the bands I'd pick.
New war metal? Yeah, it exists, with the above caveat about stylistic purity. War metal's (and bestial black metal's) fidelity to black metal is not likely to produce anything really new and interesting, since I think it is pretty saturated at this point, but that doesn't mean it can't be a minor influence. New war metal-inspired albums like Diocletian's Gesundrian and Truppensturm's Salute to the Iron Emperors are great albums, semi-interesting and totally enjoyable. But the image of black metal held by war metal makes these albums... not really war metal. Both are more black/death of the usual variety (Diocletian used to be more rigidly war metal, as on Doom Cult). Truppensturm's guitar lines are way too melodic to be war metal. They play very down-tuned diatonic scales with a heavy as shit guitar tone and war metal style vocals. They are just not chaotic and filthy enough to be war metal.
So why not do away with war metal altogether, using it as an influence but abandoning its distinct identity? Well, war metal is a continuing position, a microgenre rallying-point. I can accuse war metal of narrowness and then define bands as war metal or not using that very narrowness and there is not a contradiction. What I'm doing is arguing for a different understanding of black metal. It's the fidelity that matters, what it means to be "true" to black metal. War metal has one understanding and second wave black metal has another.