That was pretty much the backstory to our Star Wars campaign 30 years ago (except we didn’t know about the Vong then and so the threat was actually from Thrawn’s people, he was a scout and infiltrator). Also, my version of Palpatine wasn’t a Force user (he just let people think so; his Vader equivalent was a bishonen idiot who got ganked by the PCs in the second session) and turned out to be the father* of one of the PCs, who took this very seriously and made herself Empress after Thrawn killed her dad.
*Her mum was Mon Mothma.