Her "memory" is a major misfire. She is screeching on those high notes and her body movement and gestures are exactly the same as Norma's in Sunset Blvd. Could she be cast in another musical lead role? Her ability to project character seems extremely limited to rock concert style performing. Even though it worked for Sunset, I don't think it works for Cats or most other shows.
Everyone seems to forget Sunset Blvd has lost money in several productions. The story does not appeal to a wide audience, even the movie never had wide, wide appeal. It is a tragic downbeat story about three sadly deluded people -- Norma, Max and Joe. The score has three strong solos, two for Norma, one for Joe, but the ensemble numbers don't invade the story, they stand outside the world of the mansion, as does Betty - so they seem like they are from a different musical score in some ways.
True, she made the show work with her amazing vocals, but it was never going to be the big sellout with premium priced tickets making up the box office necessary to pay back costs. This production cannot tour without her, so it had a limited chance of recovering its costs.
Perhaps the days of money making revivals with full casts and full orchestras are over. That is very sad, but seems to be the case. I am so glad I experienced Broadway theatre when the orchestras were all over 20, the cast size was always above 35, and the sets, lighting, costumes were so professional and artistically first class. Like many things in the current world, those golden days seem to be over with.