What if the "Empire" become "good guys" in the new Star Wars trilogy?

Since the rumour emerged that John Boyega's character would be a Stormtrooper (which has now been seemingly confirmed by the trailer) we've all assumed that he's a 'baddie' who becomes a 'goodie'. Great idea, and an original one for the saga, but what if its not so straight forward? What if Boyega's character is actually a way for the audience to sympathise with the "Empire" (or whatever they're calling themselves nowadays), and what if, over the course if the new trilogy, the Alliance and the new Empire actually join forces to defeat a greater foe?

Maybe we start off the trilogy with an uneasy armistice between the two sides, one that's been in place since the defeat of the Emperor, and then the old conflicts flare up again for some reason, and we get the usual battles between X-Wings and TIE Fighters, but then a new enemy emerges (a Sith army for example) and Leia manages to forge an alliance with an old Imperial officer who is now leading what's left of the Empire (Sidow's character, perhaps?) to fight the new forces of the dark side.

It would be a juxtaposition to the prequels where the Clones start off as "goodies" and go bad (in a manner if speaking). And after all, we've already seen the Rebellion beat the Empire, do we really need it to happen again? Maybe this time the battle is even bigger.

Who wouldn't want to root for Stormtroopers for a change?