Logically, the original films cannot have happened at all. The entire timeline has been messed around with. Think about it. Wolverine's interference in 1973 has affected all of these things:
*Magneto gets out of prison early
*Trask is not killed
*Sentinel program is cancelled
*Charles gets out of his personal funk much sooner
*Mystique is redeemed (maybe?)
Those are the biggest changes, but there will be smaller ripples as a result. For things to happen as they did, history needed to play out as it did before, but with the aforementioned big changes, these next events are very unlikey to happen:
*Stryker probably does not form Team X, or if he does, it does not include Wolverine, meaning no Deadpool
*Magneto would not wait until 2000 to start acting against humans, so the entirety of X-Men no longer happens.
*Wolverine will become involved with the X-Men in the '80s (as per Apocalypse)
*Because the first film doesn't happen,X2 is unlikely. Styker's actions against the mansion probably do not occur, as instead he probably acts against mutants far sooner.
In reality, the events of The Last Stand and The Wolverine are probably the only things that will still happen. Yukio will still come for Wolverine to say goodbye to Yashida, so it follows that the adventure in Japan would still happen. Worthington Labs would still invent the cure (unless a future film affects this), so the events of 3 would still have to happen, just without the Pheonix aspect.