To be hornest, it has been a while since there's been a head to mount on a spike...
Azshara: not dead, Jaina: not dead, G'hun... not even sure where the head ends and the body begins, ? Kil'Jaden: turned to smoke, Gul'dan: more smoke...
Argus the titan actually had a head. No reason we couldn't mount that shit. But at the same time, I think the actual essence of Argus is still alive. After all, the other titans were still "alive" after being killed by Sargeras.
And G'Huun should have been put on a giant fishhook.