Definitely not Micky, the Disney department in charge of his image is very strict of his usage. The Micky we have is "Sorcerer's Apprentice Micky," and no other. If we wanted a classic Micky, or a Steam Boat Micky or Kingdom Hearts Micky (god willing), we would have to have a completely different figure, not even a costume change disc will do the job as "Sorcerer's Apprentice Micky" never changed costumes or appearances in Fantasia.
My vote would go for Baymax since the only evidence points to this. We know there's a gray Baymax, and right now, no word on more discs or a different skinned Maleficent (as much as I would want one).