They almost did so a while back when they said she had the Havana Syndrome.
Actually, there is the scenario existing that at the right-point....Feinstein would announce she is retiring, and Gov Newsom could appoint VP Harris into the Senate seat...then opening up the door for Biden to select a new VP (probably Gov Newsom), and just as the 2024 primary opens...Newsom steps in as the prime candidate.