Bryan Singer has been trying to get the band back together for X-men: Days of Future Past, and so far he's been pretty successful. Joining the X-men: First Class crew is many of the older crew with Ian McKellen, Hugh Jackman, Patrick Stewart, Ellen Page, Shawn Ashmore, and Anna Paquin confirmed to reprise their mutant roles from the original trilogy. One name noticeably absent has been Halle Berry, with many suspecting she would never get another shot to spout some truly awful dialogue as Storm again.
But speaking with Shadow and Act, Berry was reportedly "90% sure" she'd be back, noting that contract negotiations are far enough long that they won't be falling apart now. Filming begins in April, and Singer would obviously want to have everyone locked in long before that. I still expect him to somehow work in Famke Janssen and James Marsden as centerpiece mutant couple Jean Grey and Cyclops. Singer recently talked about fixing many things badly broken by X-men: The Last Stand, and what happened to them would have to be considered a top priority. The time travel nature of the plot gives him every opportunity to do just that.
X-men: Days of Future Past opens on July 18th 2014.