Originally Posted by psylockolussus
It doesn't matter if she has more value as an Avenger.
Outside of the comic-book community, Scarlet Witch is more well-known as a X-Men character and FOX has the movie rights to use her in the films.
I'd be as interested in seeing Whedon's takes on Wanda and Pietro as much as Singer's. I've a feeling Marvel might deviate a lot more from source than we might think, because of the success of Iron Man 3 despite its total deconstruction of the Mandarin.
Fox has been a bit late in bringing in Magneto's kids. One good way of getting round the fact they've never been mentioned is to have them as his children in an alternate reality where things turned out differently.