The funny thing about all of the terminator comparisons that people are drawing with Days of Future Past is that the original Days of Future Past storyline in the comics pre-dates the Terminator movies by several years. (It came out in 1981, Terminator 1 dropped in 1984). And the comic heads here probably know already that Kitty Pryde went back in time in the original storyline, not Wolverine or Bishop. At that time, the characters of Bishop and Gambit hadn't even been
created yet. (Gambit first appeared in 1990, Bishop in 1991. The original Dark Phoenix/Days of Future Past stories dropped in 1980-81.)
I think what it really comes to is that the series as a whole definitely suffers by holding on the continuity from those garbage movies known as The Last Stand and Wolverine: Origins. First Class and Days of Future Past are
movies on their own but by holding on to that continuity that was already a tangled mess to begin with, they couldn't use Cyclops, Jean, Iceman, or Angel since they would have been way too old.
They also couldn't send Kitty back in time because she wouldn't have been born yet since they were going from the present to the past in the movie, as opposed to traveling from the future to the present the way they did in the comics.
Those two movies would have been way better had they established First Class as a full reboot from the jump IMO. Seeing the OG team on the big screen in that movie would have been
, and Kitty's long overdue to get her shine in the films as far as Days of Future Past is concerned. I think she's better off sitting this one out though. They need to establish the likes of Storm, Cyclops, and Nightcrawler first and let them mature a bit before they introduce Kitty, who's best known as the "kid sister" of the group.
(Angel would
definitely need a new costume if they ever made a movie about the original X-squad though
)
tl;dr: First Class and Days of Future Past would have been better movies if they had set up First Class as a straight reboot instead of basing it off the crappy continuity of X3 and Origins.