I personally don't see why they wouldn't include a villain in a play set pack. I think it really depends on what characters are available for that story. If Pirates of the Caribbean had been a stand-alone play set (instead of being included with the start pack) either Davy Jones or Hector Barbossa would have been included with Jack Sparrow. If there was a Star Wars Rebels play set, I could see Hera and an Inquisitor or Agent Callus being included. And I could especially seeing including a hero/villain in a Marvel play set. I don't know if it's likely, but I don't think it's off the table either.
@vynsane The one male/one female play sets are something they started for 3.0, which I really appreciate. Although it's too bad they didn't do that for 2.0, because then we probably would've had White Tiger for the Spider-Man play set.
Merlin! Merlin! Merlin! Merlin!