Source seems to be true, or something like that!
DailyMail reports that producers are "...hoping to land British star Emily Blunt to play the villain in the next Iron Man instalment." Someone says that she would be Madame Masque. We can remember that she was the first choice to be Black Widow but she drop out leave the role to Scarlett Johansson.
This fact plus her apparence on Captain America: The First Avenger let us think that Emily still have good relationship with Marvel Studio.
"They are desperate to have Emily as the villain in the next Iron Man film and will continue to have Gwyneth playing Pepper, though she won’t feature in The Avengers."