In case it makes anyone feel better, it's worth noting that although this mansion apparently will not survive, there are many other mansions on Long Island's so-called Gold Coast that are both astonishingly grand and open to the public, and which were inhabited by the same crowd that Gatsby would have been a part of. So the physical remnants of Fitzgerald's inspiration aren't entirely lost. There are several great books about these places -- both the ones that are still around and the ones that didn't survive -- that are full of strange tales about the extremely wealthy and often eccentric people who lived there.
I posted some pictures from my visits in these two blog posts (in case anyone is interested!):
Planting Fields Arboretum & Coe Hall: http://simonandivan.blogspot.com/2010/0 ... -hall.html
Old Westbury Gardens: http://simonandivan.blogspot.com/2010/0 ... rdens.html