With the set being called "Spirit of Rebellion" and Rebels being under represented so far in the game, I actually think there may be more Rebels characters and content than we might have been shown so far.
1. Chirrut Imwe
2. Old Ben
4. Anakin Skywalker (AOTC) - Mace Windu is a good guess, too, but I would think Anakin would actually fill out that sort of "mid-level" character role pretty well.
1. Mon Mothma
2. Cassian Andor
3. Hera - I sort of wonder if she'd go here or in yellow? But red makes more sense to give the Ghost crew more variety color-wise.
4. Admiral Raddus - Gets us another RO character. Although maybe too soon after Ackbar.
1. Jyn Erso
3. Maz Kanata
4. Sabine Wren - Just because I think they'd try to knock a lot of Rebels out in one go, here, too if they are really adding them into this wave. It'd still leave Ezra, Chopper and Zeb to do from the main crew, not to mention Ashoka.
1. Emperor Palpatine
2. Seventh Sister
3. Fifth Brother - I think it'd be interesting to release them both at the same time, perhaps complimenting each other
4. Darth Maul - MAYBE too soon? But we also have the Rebels version we can get to.
1. Director Orson Krennic
2. Death Trooper
3. Agent Kallus
4. FN2199 (Nines) - or possibly Hux? Although I don't see Hux and Krennic being in the same set. A specialized trooper with some sort of way to combat Blue Force users would be cool, thematically tying in with his stun baton.
2. Cad Bane
3. Doctor Aphra - time to get some comics people in here, and she's prime material
4. Vizago - I'd say his run-ins with the Rebels crew leave him more on the villain side, even if he has no love of the Empire either