Lets see The Dems wont remove her no matter how senile she gets because they dont want it to seem like sexism, ageism, or realism. They will let her stumble, bumble, mumble and find ways to celebrate her and themselves for being enlightened and compassionate in honoring Queen Nan of holy, sanctified LIEberal estrogen.
She is the only Democrat in Congress in a leadership role who is a woman—perhaps by design. It helps her because if the leadership were to replace her, it would be all male, and that would make the feminists mad. So maybe she deliberately did not groom a female successor.