Marsden made it pretty apparent that he has had discussions with director Bryan Singer but will not be a part of the "inbetweequel." If you don't recall, Cyclops bit the dust within the first half hour of Brett Ratner's (awful) X-Men: The Last Stand. It is still possible that we could see Cyclops return, but it won't be in Singer's 2014 attempt. Sorry guys.
Marsden had this to say about potential future involvement:
“We’ll see. I always liked Cyclops, but they have a lot of characters that they have to parcel out, spend time with each one, make sure everyone feels like they’ve been given their due, introduce them appropriately, but you could do a spinoff of every one of those characters and give them so much depth to the story line.”