I hope Dom brings his legs and just reattaches them. I remember the Xavier protocols said that to kill Logan, you had to separate the head from the body so it doesn't reattach, so I don't think the legs part would regenerate a whole upper part. I don't even like the idea of Logan being able to regenerate his lower body(ala Deadpool), but at this point his healing factor has been so amped that I wouldn't doubt they would do it that way.