In the small print at the back of the program are many funds: the Repertory Fund is one of them, which seems to support some new commissions, but also to "conserve on an ongoing basis seminal ballets in the NYCB repertory." That would seem to cover Balanchine works. Also, the Company seeks support for individual ballets, and I just checked to see that last season, Brahms-Schoenberg was supported by Exxon. (Oh great. Oil money.)
And one comment on the whole issue of "they're not doing/teaching X,Y or Z the way we used to...." last year, at one of the many seminars that were part of the 100th Anniversary -- Francia Russell, Kent Stowell, Tanner, Violet Verdy, Barbara Horgan and Peter Martins were in one -- (hope I'm not forgetting anyone), where they talked about how GB's classes changed through different periods in his life. there were some points when he paid very little attention to classes at all. Barbara Horgan also mentioned that there were several students, Suki Shorer was one, who wrote down everything that was said and done in those classes. So the point is that there is no one absolute standard, even from Balanchine's lifetime, against which today's classes, performances or dancers can be measured. It's all subjective.