As far as leaks out of Pinewood studios editing room, 9 will be focus on Kylo Ren, Vader, and Anakin's relationship. The Kylo arc will continue. Redemption, maybe. Its looking like he's spending a portion of 9 conflicted perhaps building up to a climax of redemption. Either way we have lots of Luke, Hayden/Vader screentime confirmed if you trust the Pinewood studios source.
Nothing hard on Thrawn yet, just Mike Zeroh's anonymous source and the tweet, along with the casting of a IRL duplicate of Thrawn. Its enough for me that if the Pinewood source says anything about Thrawn I will take it as a 100% confirmation. Just too much surmounting evidence in favor of Thrawn being casted in 9, including some of JJ Abrams allusions to fan fare.
The first trailer drops during Superbowl weekend and is expected to reveal Lando Calrissian, and potentially hint at either Darth Plagueis or another big bad.