Must jump in here as I used to be a children's librarian. In fact I worked at the Crown Heights branch many (many!) years ago. My role then, and the library's role always, is to bring books and reading to children who may not have anyone else in their lives to do it. I can't speak to who uses those branches now, but in a general way - for children, the suggestion that people can "easily" go to the Central Library or that in the age of computers, libraries are not needed, just doesn't hold. Community libraries offer story time for the smallest children, a safe place to do homework and get help with it for older children, a useful class outing from the schools, and a source of job or citizenship information computer skills for people who may not know how to use a huge library or are intimidated by it. Or may not even have the MTA fare to get there! Chronically underfunded and overlooked, public libraries an underserved population and always have. Not their only role, but still an important one.
I don't see how preventing private investors from owning this land is the reason to keep this as a public institution that requires increasing $$ to maintain.
The idea that the library is a resource for children and others is great, heart warming, touching, you name it. However those warm fuzzies don't translate into actually being a resource and impacting enough lives to justify the cost. If they are doing that, great, but they haven't said or shown anything to prove that they are.
Will people have to pay the museum's hefty admission fee to visit the library?