1) Barbra Streisand but a) she would never follow anyone in anything, b) she doesn't like performing live theatre and c) she has admitted to not loving the material to begin with.
and
2) Meryl Streep, although the box office magic would begin to diminish in a couple of months because it would be more of a novelty than a perfect match. Still, a 3-4 month run would probably outsell Bette.