I say “may,” because the show is in the early stages of development, so anything can still happen.
Peggy Carter was played by Haley Atwell in Captain America: The First Avenger and Atwell will reprise the role for a short that appears on the just-released Iron Man 3 Blu-Ray (Affiliate). That short has the potential of becoming a sort of pilot for the Agent Carter series. A writer is still being sought and there is no word on if Atwell would still play her.
[via IGN | Order Iron Man 3 on Amazon.com (Affiliate)]