I've no idea what they may think of doing for a sequel, but I don't doubt that there are still serious plans for one with how well both The Wolverine and Days of Future Past were received.
As far as Silver Samurai and Liev's Sabretooth go. I think a return for Liev is far more likely. People still call for his return and though he is associated with the lesser Origins movie, he still sees support from the fanbase for a return. I personally find his Sabretooth to be more interesting that Tyler Mane's. Though that's not particularly hard given Mane's Sabretooth was a near mute.
I don't know if they'll actively address the changes from DoFP, but I don't see them actively going against much of the film, especially the main villain from the film, considering its success. Though I did think it was a shame they had the real Silver Samurai in the movie as a non-mutant and killed him off.