Outside of Sabretooth, I'd say they could just ignore ORIGINS all together.
So? Just because they could ignore Origins: Wolverine doesn't mean that they are, and we already know from The Wolverine - and from statements from Singer himself - that they're not.
"Despair is for people who know beyond any doubt what the future is going to be. Nobody's in that position. So despair is not only a kind of sin - theologically - it's also a simple mistake, because nobody actually knows." - Dr. Patrick Curry
"There is no "supposed to be." It's an adaptation, a word that literally means change. Why bother making a new version if it doesn't offer a fresh approach?" - Christopher L. Bennett