FFG has said repeatedly that they have no intention of adding the Clone Wars/Prequel era into this game.
I see this stated a lot, but never with an attributed official quote from FFG. If you can you provide one, I'll be satisfied. As an aside, I still advocate a separate but cross-compatible Clone Wars Miniatures Game, not just adding prequel ships to X-Wing.
https://community.fantasyflightgames.com/topic/114870-no-prequel-ships-settled/
"We're not planning on integrating anything per se in the style of, for example, the Clone Wars cartoon, but with that said, vehicles, characters, storylines, etc that came out of that, those cartoons are part of Star Wars IP [intellectual Property license] in general, and I can't speak whether some of those ships that are shown today were maybe in the cartoon. I haven't seen them all, so there may be things where you sort of say, ah! that's from the cartoon, they're looking at the cartoon.
More generally we're looking at the sort of game as it is, the Galactic Civil War going way forward, and we're going to try to, we have a significant amount of content, and we're going to throw in some new content with the new cartoon set in that era. We would not ever put out a product I think that would like the cartoon characters which has this very unique kind of look and stylization to them, but obviously we're thrilled if there was some awesome new type of starfighter that was revealed to us in the Rebels TV show, for example, we would take a very hard look at trying to integrate that into our future plans."
While that doesn't mean we won't get anything else that appeared in that era (we did get the Hounds Tooth after all but it didn't originate from those stories) it's pretty much a given there will be nothing widespread. The factions alone are troublesome. Separatists and the Republic aren't coming to X-Wing. You would need some type of additional storyline to pull most things from that era and have it fit. Scum seems the best candidate but again, what are you bringing in?
Interestingly enough we now have the Gozanti and the Ghost and TAP are due out within weeks. This is a year and a half from the time he made those comments (which were also approximately 2 months before the show premiered. 17 months from debut on TV to when you have the Ghost in the game is pretty substantial. That is a bit of an indicator as to just how long it can take from the time you see a ship on TV until it's in your hands.
(& Maybe) 