Bryan Singer teases X-Men characters

Bryan Singer is the ultimate tease! Today, IGN spoke with Singer an asked him if he wanted Cyclops and Jean Grey to appear in "Days Of Future Past".
  
"Who wouldn’t?," he laughed, mysteriously. "Who wouldn’t? That’s all I can say."

James Marsden and Famke Janssen who played Cyclops and Jean Grey in "X-Men" and "X2" before they were both killed off in Brett Ratners "X-Men: The Last Stand". However, considering the time-travel story arc used within "Days Of Future Past", both characters could easily return to the franchise.