There is some of that already with the Naboo celebration being the Emperor's theme up tempo and sung by children and Anakin's theme clearly being a variation on Vader's.

I wish they could have built on that.

The Imperial March should not have appeared until the end of ROTS and Anakin's theme should have slowly clawed towards it as he fell deeper into the dark side (not that he is much in the light side in the PT we saw).

I would have liked to hear the Imperial motif from ANH as the clonetrooper's theme too and maybe a bit more of the droids motif from ESB (but I'd have liked to have heard that in ROTJ too).