There is an theory, that on blizzcon heroes what will be announced will be connected from Diablo universe. This makes sense giving the fact, this year Blizzcon will be focused mostly on that universe. So the question is who?
Another theory suggests that Imperius along with Inarian as announcer from battlefield of eternity like was Beleth with Mephisto. Also leaks from march suggesting Belial as well, but issue is...
Specialists will be probably an history with class system rework, so Belial may end as assasin.