But imagine how much it'd lose per week, if it tried to run with a mere mortal who's not well known. Better to close in March than risk losing some of the money that was made when Lea joined.
I can't help thinking that, as long as she is selling out or at least still doing really impressive business, Lea would probably extend unless she has a seriously better offer with a tight time window. After all those years of saying that all she ever wanted to do was to play Fanny Brice on Broadway, I would think she'd want to play it longer, (a) to get it out of her system), (b) to continue to add new fans for future Broadway and film appearances, and to have ANY chance, however remote, of getting a special Tony.
Re the latter, I only mention that because others have posed that question on this site. I personally think that is a super-up-hill battle. They really haven't given one of those in years and years (at least, that I can think of...I remember Pearl Bailey and Mary Tyler Moore getting special Tony's for roles they did not originate, but at least both of them were in shows in which the original leads previously received Tonys for their performances). The fact that Streisand never got a Tony for playing Fanny could present an issue. Even there, however, I guess one could argue that she did get a Tony for Funny Girl since there was no other reason to give her a special Tony, since the last time she was on a Broadway stage was when she left Funny Girl, and no one was going to give her one for I Can Get It for You Wholesale.