Yup, Sabertooth is dead, no dancing around it for writers, it was definitive. Wolverine chopped off Sabertooth's arm with the sword, Sabertooth held his arm to the stump out of instinct and the arm fell right back down, it didn't attach. Wolverine commented that it negates healing factors. Then Wolverine said he'd give Sabertooth one last chance to stop him, Sabertooth growled and said "do it..." and Wolverine chopped his head right off, and left Sabertooth's body to the wolves instead of burying him.
Then Wildchild told Wolverine all about Romulus, and how he's been messing with Wolverine's mind for years (must be telepathic), and how Wolverine represents the best of all of them, then Wildchild disappears and it ends.
So Sabertooth is definitely dead, had his head lopped off with a healing factor negating sword.