It is my hope that FFG will obtain licensing rights to the prequels within the next couple of years so that we can have Republic and Seperatist factions. I know a lot of people hate the prequels, myself included, but the starfighters in those movies were actually pretty cool, and they would bring a lot of potential to the table with generic Clone/Jedi/Droid pilots.
If FFG can't get licensing to the newer movies, in a few years they will be stuck either rereleasing old ships with new upgrades, or making up their own ships.
But what does any of this have to do with the X-Wing being a viable ship?
They already have the rights to the prequels. Their license is all inclusive. I think Christian Peterson even confirmed this at Gencon. You can see plenty of PT imagery in their other games. They just choose not to make PT games, rightly assuming that it is a bit of a divisive issue. And the powers at top are refocusing on the OT for the new movies.