I think these side movies are going to flop actually (on the whole, I'm sure the first one will do ok). I think Disney is going to be very surprised at how little general audiences care about "side stories" set in corners of the SW universe. I just have this feeling that if it's not a "real" star wars movie, they're going to treat it like that theatrical Clone Wars "movie" (which was the first two TV episodes packaged for theatrical release).
Of course i have no idea on the execution. They could make it super awesome I suppose. Actually if they do the Yoda movie, the best bet might be to make it overtly a kid's movie.