I also like Anveena
You know, I completely disregard the 'one Legion all realities'. To me, this doesn't exist. Up until now, ignoring it hasn't created any lore flaws, so I'm going with it. If any problems arise, I'll try to explain my way past them.
Thus, Archimonde dies physically at Hyjal and later reformed in the Twisting Nether because he is a demon. We haven't heard from him since. The one in WoD is a completely separately version of him, who never got to see Hyjal again.