As for "X-Men Origins: Magneto," Fox has stated before that they are putting the movie on hold and want to see how "X-Men Origins: Wolverine" does first. It seems that David Goyer has written a script but McKellen still hasn't seen it.
"I haven't read a script, no," McKellan said. "It's not come my way. I'm here and ready and waiting, but I think if they do do a spinoff of Magneto, it'll be about the young man, the young Magneto."I suppose the question is, if they do make another Wolverine movie, would they make a Magneto movie at the same time or would it get pushed back further? Would the movie just feature a young Magneto or would they span his entire life? That could prevent future spin-offs if they tell his whole story. Plus he is a complex character and it'd be a shame to squeeze it all into one movie. Guess we'll have to wait and see what happens after Wolverine storms the theatres.
The success of the upcoming prequel film X-Men Origins: Wolverine, which stars Hugh Jackman, could determine Magneto's prospects.
"If the Wolverine movie does well, well, probably they'll just make another Wolverine movie, won't they?" McKellan mused. "I was told that there would be a Magneto spinoff, and anything else I'd say would just be guessing. That was a long time ago."