Glad Atwell is playing old Peggy. We discussed this two years ago in our interview:
Jeffrey Harris: We heard from director Joe Johnston in the press conference that Peggy Carter is still alive in the present day. She's still alive and in her 80's. So are we going to see you doing an elderly Peggy Carter in Avengers?
Hayley Atwell: Oh god, I hope so. It'd probably be cheaper to get someone who was in their 80's wouldn't it as opposed to putting me in prosthetics for six hours everyday.
Jeffrey Harris: No, we want you to do it.
Hayley Atwell: I'd love to. I haven't been approached yet officially, but if I was, I would absolutely run at the chance.