Re: The #4 movie - which movie series will have it first?
That's a fair guess, I suppose, but it's not really based on anything. There's no reason why they can't come out with an X-Men 4 after DOFP, just like they can come out with an Iron Man 3 after Avengers. You could call Avengers the sequel to Iron Man 2, since it continues the same exact story, just adds in other stories with it, but at the end of the day, because it's not *just* Iron Man's sequel, it's something different, it's a team up movie, and they would naturally follow it up with Iron Man 3, not Iron Man 4, or even Iron Man: Extremis even though The Avengers' story is integral to appreciating that of Iron Man 3.
Notice how those who suggest a different X-Men for can/will exist are basing it on quotes from the filmmakers and other franchises that have done similar things narratively, while those who suggest DOFP is X-Men 4 and numbering days are done are just "I doubt it" and "this forum poster said they're done."