I could see a prequel being interesting. It would undoubtedly be a lot flashier and bangier than one would normally associate with the first Doctor, and I don't know if it was ever established how long before that he stole the TARDIS, but if done right it could be a cool and exciting story. One potential drawback is that they wouldn't be able to use any of the established villains, but that's not necessarily a bad thing.

I wouldn't be surprised if they want to keep the new series idea of the Doctor being the last of his kind, however. That seems like the sort of background feeling Hollywood would enjoy.