What "special promotional piece" could be at the end of X-Men: Days of Future Past?

My theatre got their copy of X-Men: Days of Future Past.  They always come with instructions so we know when to bring the lights up, what trailers to attach, etc.  To inform us when to bring the lights up, they use the following format:

Feature Run Time: 2:05:02

End Credit Offset: 2:00:49

So using this format, we would program the lights to turn themselves on 2 hours and 49 second into the movie, so right when the credits start the lights come up.  Now with after credit sequences, this can get tricky.  With Marvel and Sony's current format, they give us the offset time after the first credit scene.  For example, in the Avengers the lights came up right after the scene with Thanos.  In Amazing Spider-Man 2, the lights stayed down until after the X-Men scene.  With Days of Future Past, they don't want the lights to come on until the entire movie is over, credits and everything.

This is uncommon.  Most of the time, the lights come on before the second post-credit sequence.  The lights came on before swarma in Avengers, before the Bucky sequence in Captain America 2, and before Thor's return to Midgar in Thor 2.  It's strange for them to request the lights to come on after the very end of the credits.

If you look closely, there is a message from Fox saying there's a special promotional piece at the end for guests to enjoy.  I wouldn't exactly call most post-credit sequences promotional.  There are a few exception, like the Avengers promo at the end of Captain America and the X-Men promo during the credits on The Amazing Spider-Man 2, but generally they aren't exactly promotions.

You could argue that some are promotions, Iron Man 2 had Thor's hammer, so you could say that's promoting Thor.  Really, it depends on what Fox meant when they said special promotion.  It could honestly just be the wording they used, but I'm thinking there's more to it than that.

Let's assume it is just an after credit sequence.  In the past, Fox hasn't done anything too crazy with them.  In X-Men: The Last Stand, it's revealed Magneto has gained his powers back after losing them from the mutant suppression shot.  X-Men Origins: Wolverine had Wolverine drinking in Japan, possibly hinting that his next movie will take place there, and it did.  In the film Wolverine, the after credit sequence shows that Xavier is alive, and working together with Magneto to save the future.  This scene pretty much gives the basic plot to Days of Future Past.

Looking at possible future X-Men titles, I think the best guess is there is going to be something with Apocalypse in this "special promotion".  Fox has already announced their next X-Men film, title "X-Men: Apocalypse", so it would be no surprise if that is the after credit sequence.

Fox has also announced a sequel to Wolverine.  The film will be released after "X-Men: Apocalypse", so I find it unlikely that they would be hinting at anything relating to it in this film, but I could be wrong.  There is also talk of an X-Force film, so maybe this will be there way of announcing that X-Force is being officially made, but I bet X-Force is formed during "X-Men: Apocalypse".

There is always the possibility I'll be completely wrong.  Maybe its a promotion for another Fox title unrelated to X-Men.  Obviously Marvel didn't start the trend of having post-credit sequences, but they have certainly made it more mainstream.  During my early days of projection, I hardly ever had customers ask if there is anything after the credits.  Now, I assume about 20% of all customers ask if there's something after.  If this scene turns out to be anything less than something related to Apocalypse, or at least Wolverine, I have a feeling people will be disappointed.  Either way, I'll let everyone know tomorrow in a spoiler free fashion!  Just for fun, here is the projection instructions for "X-Men: Days of Future Past"!