I don't see any reason she can't be replaced immediately.
Me either. Worst case scenario, Trump loses the election (disastrous, of course). He's still president from today till, what, January something? That's like four months. He should nominate someone tomorrow, and let the Senate vote on it. The Republicans control the Senate process, and can set whatever time limit it deems appropriate. One month should be a more than sufficient time to deliberate.
