Im not sure if it would work the same in Star Wars. The only reason the marvel movies had the after credit scenes was because the individual stories were leading up to the avengers. Now, the aftercredit scenes in the Phase 2 movies will tease at how things lead up to Guardians of the Galxy and Avengers 2. To my knowledge, these spin-off movies are standalone tales that dont lead up to anything. I certainly dont think we'd have an after-credit scene that would lead in to another spin-off movie. If anything, we'd get an after credit scene that somehow leads up to something in Episodes 1-6. For example, i could see an after credit scene in the Yoda movie that shows Yoda using the force to draw lukes X-wing to his location on Dagoba. But i couldnt see them doing an after credit scene of a Yoda movie that teases something in a Boba Fett movie. It just wouldnt make sense.