The Oil Drum: Local

"Eventually, this rail service could also take advantage of Staten Island's restored freight rail network and reach out to the Northeast Corridor line as well, strengthening Staten Island's connection to the regional rail network."
Unfortunately, that is unlikely to happen, since subway or light rail type rolling stock is not allowed to share tracks with freight trains, unless the passenger cars meet ridiculously high collision standards (basically, the train has to be strong enough to stand a 10 car train on end without the bottom car bending). And I think this whole "light rail" business is a bad idea, since Staten Island already has a perfectly good heavy rail line, and indeed much of the heavy rail infrastructure is still there along the North Shore Line, notably the viaduct through Port Richmond. On the other hand, they could extend the HBLR over the Bayonne Bridge, and provide a transfer with the North Shore Line. It's unfortunate that thanks to Bob Moses it is impossible to run a subway line over the Verrazano Bridge, but it might be possible in the far future to build a tunnel from St. George to Bay Ridge.
Another option, somewhat from the realm of fantasy, is to replace the Staten Island express buses with light rail, with street trackage feeding into a line in the middle of the expressway, and then going over the bridge, down the Gowanus Expressway in Brooklyn, and then through one of the Brooklyn Battery Tunnel tubes into a street line up, say, a Broadway that has been dedicated to pedestrians and light rail.