I really wonder how they're going to play the Ghorman Massacre and Mon Mothma's subsequent actions. Rebels is cannon, and she calls Paply out as a "lying executioner" and then has to flee Coruscant. She is aided by Hera Syndulla (the dullest part of the Ahoska series), and taken to safety by the Ghost (ship) and the nascent Gold Squadron.
They take her to Dantooine and she gives the "Declaration of Rebellion" speech on board the Ghost with Hera and Ezra Bridger right next to her, and when it's over, she sends out her coordinates and all these ships start appearing to join up. Bail Organa is also prominent.
If they go with the Legends version of events of the Ghorman Massacre, we're going to get a cameo by Tarkin in here as well.
It doesn't seem much in Gilroy's wheelhouse to be including Hera and Ezra in his show, although he did have Ponda Baba and Dr. Evzan in Rogue One, along with R2, 3PO, Bail, and General Dodonna. Will Barristan Selmy return as General Dodonna? Homeboy is 77 years old, so not sure.