----------
I don't think it will be Diablo 3 as the Diablo team left Blizzard and as far as I know they had the rights for a Diablo 3, it might be another Diablo thing though, but not directly a "Diablo 3". But Blizzard ofcourse could have bought back the rights, who knows.
----------
Riiiight... But, alas, this post was made 3 yeas ago. Now it's ironic.