I've had this theory for a while, and I'd just like to get this out there. Everyone should know that bending removal is done by energybending, so shouldn't it be able to be restored with the same method? That would mean that another person able to use energybending (the Avatar, for example) should be able to restore a person's bending. So there's hope for people like Lin Beifong (who did NOT deserve to have her bending removed) after all!! Maybe later on Korra could figure out a way to do that. Just a theory.