When will she tap Joe on the shoulder and say "okay Joe, time to retire"?
Will she do it that way or will she use the media to do it? Leaked stories of his mental decline. Comments from her such as "Joe is easing into the idea of retirement, it will take time, but he's getting there. He knows it must come and we're wanting him to announce it when he feels comfortable, we owe him that."
Eventually she will say "if we need to remove him from office using the 25th amendment we will do that, because we have sworn to uphold the constitution."
Which scenario do you see happening?