On a note regarding "Heros", you kind of need to have them. Or at least normal, named units like Kerrigan and Raynor, or you'll have a story beig told by... nobody, except nameless units. Thats no fun.
I forsee the Xel'Naga having something to do with the new game, as mentioned in brood wars. As it stands now, the Zerg pretty much rule the sector. The Protoss are shattered and the Terrans are just barely holding them back.