I have a feeling the sith will be in the new trilogy or some form of dark force. I am more leaning on the sith the reason why because there will be a lot of new people watching the new trilogy and I guarantee you if there are no dark side force users or sith in some from people will be upset. If the story is good without them I would not really care but I personally would want them in the new movies. I am a sith fanboy after all
eh this is just my opinion.
On the one sith yeah if you have old sith lords telling you that your sith order sucks you have some problems. I personally don't like them but if one of the original dark jedi acknowledges (Xoxann) you and trains you in the ways of the sith I would call them a sith personally even if their order sucks.