There was this girl at Blizzcon who asked why we don't get Pandaren Druids, and at first I thought it would be a bad idea to add more and more Druid races. Kosak also said that, they weren't around to be taught by Cenarius. But Worgen and Troll Druids are already a very special form of Druid. The whole Worgen thing in itself is messed up. They were originally Night Elves, who were stuck in the wolf form, but the Druids we play are Humans, who are afflicted by the curse. Then they made up that whole harvest-witch thing to make more sense of why Druids were practicing Druidism before they turned into Worgen, and it's nice and all, but there's still no real connection to Cenarius. Troll Druids revolve around the Loa, also no real connection to Cenarius.
So why not make Pandaren Druids based on the August Celestials. Ox (Niuzao) could be tanking form, tiger (Xuen) could be cat form, cloud serpent (Yulon) could be flight form and crane (Chi-Ji) could be traveling form.