I really hope that Bill is just herself too; we've had enough special companions who approached timelordage.

As for the other speculations, I have no idea what's in store, or what they're doing with the Master. I do think the Doctor turned up at Missy's execution to save her, but I hope they do tell us who (of probably a vast number) wanted her dead. She could be reconsidering her past, or acting the part, but I do hope they do something interesting with her (pr Simms-Master) and the Doctor.

I also hope Nardole hangs around, despite the other major changes. I do enjoy him.