Lansbury already skipped the chance of reprising her role back in the 90s when the GHMC (I believe) did a concert version at Carnegie Hall. She narrated the show instead.
I've said about a hundred times that Meryl Streep, Neil Patrick Harris and Jane Krakowski would be absolute perfection for the three principals. However, it being Encores! I assume it'll be more like Christine Ebersole (please no) or Marin Mazzie, Jason Danieley (whom I wouldn't mind), and Jenny Powers.
"Some people can thrive and bloom living life in a living room, that's perfect for some people of one hundred and five. But I at least gotta try, when I think of all the sights that I gotta see, all the places I gotta play, all the things that I gotta be at"