UPDATE: Hugh Jackman has technically been "in talks" this whole time (even if I was confident about it) about appearing in Days of Future Past, so he still could have backed out of it. Thankfully, Bryan Singer has confirmed via Twitter that Hugh Jackman is really coming back to play Wolverine...you know after he finishes playing Wolverine in that other movie. Original story below.
While Hugh Jackman is technically "in talks" it's all pretty much probably going to happen most likely. Since Wolverine has somehow squirmed his way into each one of the current six X-Men films (because he's awesome, that's why), it was pretty much a given that he'd show up in the seventh installment with the news that Patrick Stewart and Ian McKellan are coming back also. You can't order just rice and beans, you have to get the whole enchilada plate. I'm hungry.
This also means that Days of Future Past is most likely going forward with the time travel plot of the comics (I'm still pretty adamant about not including Kitty Pryde). This also means that DOFP is going to try and connect all seven films together in order to fix a continuity that's just been destroyed at this point. Hell, take the sixth X-Men film The Wolverine, James Mangold said that it'll take place after The Last Stand (the third film) so what's going to happen there? Maybe they'll just be parallel realities. I'm perfectly fine with that.
Also with all of this time travel business, where the hell is Bishop? Or Apocalypse?