The smartest move for the Republicans is for Trump to name his appointee, and for Mitch to put hearings on the schedule that will begin right after the election, during the lame duck period.
Regardless of if Trump wins or loses, or whether the Senate control changes, the nominee would be seated sometime during December, before new Senators come in January 1.
This way the hearings don't disturb the dynamics of the election.
The Democrats have no leverage to stop any of this from happening. However they will feel very upset, because they are not getting their way, and because Republicans in the Senate are behaving as hypocrites. They will pack the court first chance they get, unless they get brought to the table before the year is over, and offered a compromise to have a better system going forward.

---