Next WoW Expansion? The Dark Below

[Maitre]

There's an off-chance this name could be used for Diablo III, but it seems unlikely.

Seems just ambiguous enough that it could be Diablo related, however, I think any "below" in the Diablo universe is more likely described as "burning," "hells," "pit(s)," "demon(-ic)," or "Baal's."

The only thing I'm sure of is that there will be no tie-in with the Warhammer universe(s) - the "grim" is missing from Blizzard's "dark."