On a serious point though, I think its too late for an X4 to happen. It won't be made while they're still doing the "prequel trilogy" which will end when? Let's say 2013-14 for Second Class? 2017 for Third Class.
Way too much time will have passed for the original actors to reprise their roles effectively. Patrick Stewart & Ian McKellan would be nearly 80, Shawn Ashmore 40ish, Famke Janssen 50ish, Hugh Jackman 50+ etc. It won't happen.
Unless they recast them all, and in that case what's the point, you may as well just 100% reboot it all