Curiously, Feinstein was incoherent and had to be wheeled into committee in a wheelchair for a while before she finally expired, still in office.
We've seen countless times that officials, whether elected or appointed, will cling onto power until we pry it from their cold dead hands.
We really need to implement age caps as well as term limits, since we can't count on elected officials being pressured into retirement by their own peers, nor can we count on the voters primarying them since it means losing the incumbent advantage.
Sadly, as with much of political reform, the status quo serves those who are in office, so there's not much motivation to implement such legislation, and the public is not great at organizing over secondary matters.