Actually, I wouldn't mind wookies. But why would ALL the rebels be wookies are beyond me. It's not like the empire isn't enslaving everyone else too. Suffice to say, Lucas has had plenty of bad ideas...the prequls can attest to that...
No, there wouldn't be rebels. The Rebel command staff all were on Alderaan, and Leia doesn't know how to contact any other cells, so Han, Luke, Leia, Chewie, Obi-Wan (he didn't die in the early drafts) and the droids fly off to the wookie homeworld, teach the wookies to fly fighters, and go off to destroy the death star.