As long as she’s breathing on her own, the Constitution gives her permission to be on the bench.....................
She can be on the bench but she can’t hear cases if she is incapacitated. IOW she can’t have someone else stand in for her.
John Jay, the first Chief Justice of the SCOTUS left at age 50 to be the Gov of NY...
so the SCOTUS didn’t start out as a lifetime job...
But RGB is not GOING back to the bench. Right now, she is reviewing the cases from her home, and phoning it in....
She may never physically return to the Supreme Court bench.