I don't think even Wolverine can survive being dissected and having his organs in jars, but maybe she's better at healing than that?
That makes me wonder if one of these super healling people were chopped in half, would both halves grow back?
If Woverine needs help, can he volntarily visit a saw mill and have two of him?
If he needs lots of help, can he jump into a wood chipper?
Yeah, like a lot of super-hero logic, Wolverine's healing factor gets sillier the more you dissect it (pardon the pun.)

But hey, I'm not saying it has to be Sky's mum, just that it's a possibility. If memory serves, there's a fair amount of precedent in comics for immortal/slow ageing characters to have regenerative healing, not just Logan. Vandal Savage leaps to mind, as does Mystique, Lobo as well as certain versions of Sabretooth and Martian Manhunter.
With that in mind, I think it's fair to say that nothing we saw done to Sky's mum totally precludes the possibility. Of course it would raise the rather gruesome possibility that believing her dead, Cal buried her body and she had to claw her way out of her grave once she was done regenerating.