[MyNameWas]

First off, I doubt blizzard is going to start basing the Diablo 2 universe off Lovecrafts work. That would be copyright infringement unless they got the rights, and I doubt they'd do that anyway. Because its the Diablo 2 universe, not the LoveCraft universe.

Second off, I would like to point out that the Diablo universes prime evils are not neccesarily out of the picture. They are devils. They simply went back to where they came from. They didn't "die" because they were never "alive" and hence cannot be "ressurected". They could re-enter the daiblo universe, if there was a way. That was the point of destroying the worldstone. Take on corpreal from, or to be more explanatory, spirits gathering up elements around them to from bodies. Or, in the case of the soulstones, possessing humans

For Magius:
Diablo 2 is about killing devils. NOT SERVING THEM!!!
Serving devils results in the loss of the soul.
And besides, if were talking about the D2 universe here, which your not, they don't work with humans. They corrupt or kill them.
And I will use the term devil, and not demon, because the word demon derives from the Greek word DAIMON, as most educated people know, which means any spirit, be it good or evil.