^ Many of the people have been saying for a long time how DoFP "erased" all of the X1-Last Stand and Origins movies, and to a degree, they are correct, but to a different degree, they are wrong.
Yes, none of the stories we saw in X1, X2, last Stand and Origins will now happen in this new timeline, but there are still many different things that stand, even if the story doesn't happen.
A very important piece of this is the ages of characters we have seen. Other than some stupid things, like the Cyclops and the "Emma" we saw in Origins (can we just totally forget that one movie?), the ages of characters matter.
Someone above mentioned that because we will now have a young Nightcrawler with the X-Men it proves that everything is totally erased, but my counter argument is the fact that they are having a late teen-aged Nightcrawler proves that the ages of characters we've seen, even in stories that are now erased, matter.
In X2 Nightcrawler was what, maybe mid 30's? And that movie was in what year... 2004?
We also know that (assuming the parentage of Kurt) that Mystique gave birth to him in 1963 or 1964 (since Azazel - the likely and per canon father (and again, if they make Kurt's dad Erik or Beast I'm flipping out!) was killed in 1963).
That would make Kurt 19 years old or so in 1986, which would make him around mid to late 30'd during X2. This (somewhat - at least mostly, which is good for these X-movies) matches up.
As far as Rogue, look, she was like 16 years old in 2004, which would make her not even born yet in 1983. So they can't just throw her into this movie, unless they do some stupid time travel crap.
That means that IF (and it's a big if) Mystique raises Rogue, then it has to happen between Rogue's birth in 1988 and her young teenaged years in the early 2000's. Yes, this could be a good story for a Mystique 2 solo film, but there is a different story that they should do for Mystique first (her meeting and developing a relationship with Destiny) before they get into the Rogue stuff.
But like others have said, they will likely, and should, stay focused on these new characters for at least the next decade (3 movies), which should all take place in the 80's to early 90's at the latest. That means we're very unlikely to see our aging OT actors and actresses any time soon.
But, there are ways to still give us some OT stuff. I've suggested they do the two following things:
1. Create an Excalibur TV series or movie using some of the younger OT cast as the founders. We're talking Kitty, Iceman, Rogue and Colossus; and possibly an older Nightcrawler, along with some England characters, like Pete Wisdom, Captain Britain and Megan. This could most definitely work, and could have cameos from Patrick Stewart, Hugh Jackman and others.
Oh, and this could all lead to a crossover movie between the F4 and this group, once the F4 movie fails, with a story of the Excalibur group needing Reed's help to save Kitty, whose powers are causing her molecules to destabilize. This leads to the events of the X-Men versus the Fantastic Four.
2. Do a Cable Origins movie that would include his parents, played of course by Famke and James. This one, to me, makes so much sense:
