It’s probably too late for her to retire. Remember how Senate Republicans sat on the Garland appointment 293 days.
So in reality, she SHOULD retire. Trump will appoint the next justice.
The Republicans do not control the Senate... She can retire at any time and Dems currently have majority in the Senate, so no GOP sitting on an appointment.
However Dems would want the appointment battle as close to the election as possible to gin up support for their turd.