West Side and Next To Normal to shutter in early '11!?

On wednesday it was announced that the revival of "West Side Story" will be closing on Broadway in January. This is one of the first announced closings of the season. "Next To Normal" will also be closing in January and "Fela!" will shutter in January as well. I know that some shows have to close to make room for the upcoming shows. It was expected that numerous productions would close due to all of the new musicals. I was expecting "Fela!" to close due to it's numbers at the box office. But musicals like "Next To Normal" and "West Side Story" have done well at the box office. Both shows won Tony's and they have both recoupted their investments. "Next To Normal" even won the Pulitzer Prize for Drama last year and it's closing? I was shocked to hear about both closings, these were two shows that I was not expecting to close at all. I was expecting to hear that some other shows that have been performing poorly at the box office(there will probaly be more closings due to the number of new shows) but not ones that have been so successful. At least the tours of "West Side Story" and "Next To Normal" will continue to showcase these amazing productions.