Changes in leadership at the top of the various races in WoW is a common occurrence these days. The dwarves, tauren, orcs, and arguably the night elves (depending on who you considered the real bosses in Darnassus) all took on new leadership as of Cataclysm. The humans and the Forsaken as well have experienced temporary shifts at the top of their power structures at one point or another.
Today's question is simple: Who's next?
Most of the obvious candidates for replacement are on the Horde side. Sylvanas is clearly running rogue and making even her allies uncomfortable. Absentee trade prince Gallywix has been living on borrowed time from the start. Garrosh and Vol'jin have a little philosophical disagreement going that seems likely to be resolved with fewer than two of them alive. And even Lor'Themar seems to be just waiting around for a blood elf with enough ambition to unseat him.