Even if they managed an Azshara/Old Gods Expansion, as well as a Burning Legion/Sargeras expansion, what left is there? Let's see... well, they could do a proper Nerubian expansion, an expansion where they just revamp BC and Wrath (who said they had to release more levels for an expansion at this point?), an expansion with several races thrown into the mix, an expansion with a couple of classes... I see it steadily going downhill to less and less content, yet continually updated by bits and pieces.