First of all? Oh my god, the fanservice. Hahaha.

Okay, now on to the meaty bits: These are the portraits I spotted in the end which I suspect denote who's playable:

Starcraft:
Jim Raynor
Kerrigan
Tassadar(?)
Nova.

Diablo:
Tyrael

Diablo

Demon Hunter
The Butcher(?)

Warcraft:
Arthas (Pre-Lich King) (Lothar, maybe?)
Arthas (Lich King)
Malfurion
Muradin Bronzebeard? (Dwarf-on-a-Gryphon)
Sylvannus?

Abomination(Maybe the Butcher?)