Lucas Till is confirmed to be returning as Havok for Bryan Singer's X-Men: Days of Future Past.
The director tweeted the following image of Lucas Till along with the following:
"Mankind must put an end to war before war puts an end to mankind." -JFK
It's unknown if James Marsden will reprise as Cyclops.
More than likely more news will come forth from this week's Comic-Con.
X-Men: Days of Future Past has a May 23, 2014 release date starring Jennifer Lawrence, James McAvoy, Michael Fassbender, Nicholas Hoult, Anna Paquin, Ellen Page, ShawnAshmore, with Hugh Jackman reprising as Wolverine, and returning cast members Patrick Stewart and Ian McKellan.