I wouldn't want Sabretooth to be part of the Japna film, but I wouldn't mind if we got him again in a 3rd movie, as long as the story was good. a. Because Liev Schrieber was great in the role, and b. Because I feel we have not had the great knock down drag out fight we should have got from Logan and Creed in a movie yet, all of their fights have been brief.
But, I am not bothered of he does not appear again, there are plenty of other characters to explore and he has been used in two movies already.
Ideally i would want Silver Samurai, Mariko, Sunfire, and possibly Gambit, in the Japan movie.
and a 3rd movie set in Madripoor with Jessan Hoen(The Tiger), Bloodsport, Roughhouse, Archie Corrigan, O'Donnell etc
Have Wolverine involved in the gang wars, and show a darker side to him, as he has lost his way while trying to find a new identity for himself.