The Sith are basically finished, a few organizations will pop up here and there, but nothing of true significance and sustainability.
"For three hundred years, we prepared. We grew stronger while you rested in your cradle of power, believing your people were safe… protected... You assumed no force could challenge you and now… finally, we have... wait what!? What do you mean were not allowed
to return! Who the hell said... oh, George did"
No, but on a serious note - Star Wars as much as people may argue, isn't Star Wars without the dark side and good vs evil and lightsaber duels. Its iconic of any major Star Wars material and these films would suck without it. OK, so they wouldn't suck
... but they'd be a lot better with some red lightsaber wielding bad guys. I'm not saying Sith, but there were a lot of dark jedi/acolytes operating under the Empire, so why not have one of them? They had Jerec and Kyle Katarn so I see no reason why a similar thing can't be done.