Avengers 2: The Return Of Maria Hill?

Talking with The Calgary Herald about the upcoming comedy "Delivery Man", actress Cobie Smulders says that she hopes to reprise her role as  S.H.I.E.L.D. agent Maria Hill in "The Avengers: Age of Ultron" for writer/director Joss Whedon:

"I think I’m in Avengers 2, but it is very top secret. I hope I’m in Avengers 2. I didn’t get my invitation yet. Well, actually, they know I’m in it but they don’t know to what degree I’m in it.
I am really excited to read the script because they are introducing Quicksilver and the Scarlet Witch into the Avengers universe and the bad guy is going to be very interesting."

Smulders first played Hill in The Avengers and returns to the role in the upcoming "Captain America: The Winter Soldier" next Spring,

While the sequel DOES NOT follow the Age of Ultron comics storyline--in which the big bad Ultron was created by Hank Pym who becomes Ant-Man. "Kick-Ass 2" star Aaron Taylor-Johnson will play Quicksilver while Elizabeth Olsen is indeed playing the role of Wanda Maximoff, a.k.a. Scarlet Witch-sister to Quicksilver. James Spader will both voice Ultron, and he'll have to do some kind of motion-capture as well--This news puts to rest the most popular theory suggesting that Tony Stark's (Robert Downey Jr,) robot butler J.A.R.V.I.S. (voiced by Paul Bettany) operating system from the Iron Man Films would turn into the villain.

Marvel vets RDJ, Chris Evans Chris Hemsworth Scarlett Johansson Samuel L. Jackson Jeremy Renner Mark Ruffalo, Clark Gregg are all expected back

Production on the 'Avengers' sequel is slated to begin in March to meet a release date of May 1, 2015.