I've heard that they plan on doing 4 characters for each color per expansion. (I think 4 per color, per side... but I digress...)
This means we'll need BLUE characters for Rogue One.
Which means Donnie Yen! Ip Man himself!
They'll almost certainly do Chirrut Imwe !!!! This is awesome and considering he's supposed to be a force believer, but not a Jedi.... you can give him a lightsaber and he'll be so happy to finally get one!
I also think they'll have to borrow from SW Rebels if they want a "Rebellion" themed expansion, as there probably won't be enough blue characters to pull STRAIGHT out of Rogue One, so maybe Kanan or Ezra also! And maybe some Inquisitors for the Empire.