Just found out some interesting NPC's at wowhead.
As you may know, at the battle at wrathgate, during that quest, Arthas takes the soul of Saurfang the Younger, and shortly after, forsaken kills both alliance and horde armies, including Bolvar.
But still.. in Yogg-Saron vision, You can see some tortured human male - which in fact may be Bolvar.
Immolated Champion - NPC - World of Warcraft. - Bolvar
Turned Champion - NPC - World of Warcraft. - Saurfang
Check the 3d models on both links, one of them is orc male, other is male human, with typical alliance leg armor.
From what i can think, they could be one of the encounters in Icecrown Citadel.