I'd be surprised if they're introducing Leia this early, even in a cameo role and especially so soon after re-introducing Ahsoka, Rex & Vader. Then again, Bail, R2 & Threepio all showed up early on in season one, so it's possible.
Given how hard the Empire came down on Lothal, could this be one of her "mercy missions" that Vader alluded to in ANH?
I really think we're only getting three seasons.
