[Great Mind(s)]

The Last Stand can't be the mid 90s... X1 was the not too distant future from the year 2000. N'sync played in X2... The Last Stand is likely 2007 or 2008 as it says the not too distant future, not the mid-90s in the subtitle.

Singer already said he's not ignoring any of the previous movies, that would likely include the fact that Trask was around in late 2000s. He could still be present in the movie, who is to say he wasn't building Sentinels during the events of The Last Stand?