I don't have the link on hand, but in one of the (many) interviews from TIFF, she was asked about the rumours regarding her supposedly passing on the offer of Scarlet Witch (The Avengers 2), and although her response isn't exactly to the point, she more or less confirms that she didn't get that far into the process.
Edit:
Here we go (skip to 2:15):
Was [playing Scarlet Witch] ever something that was really discussed?
Not really. I mean, you know, there's lots of things that always float about and they're kind of fleeting for a second, but you know--
There was not much there?
No.