James Marsden could certainly be a great fit for another comic book character out there in the X-Men universe, and if he’s chosen for it, this would allow the actor to bring something new to the franchise– while his presence would also be a nice nod to its roots.
So bringing back an original character from Fox’s X-Men movies just doesn’t sound like it’d likely be on the table.
However, it does look like Disney’s take on the X-Men may try to differentiate themselves from what’s been established in the past 20 years, and reboot these characters in a new and refreshing way.