The interesting thing is that about 50% of the auto traffic is now from one part of the island to another and not into NYC. There are similar instances elsewhere. Stamford Connecticut and other nearby cities now have many of the office facilities that would have been in Manhattan previously.

Decentralized office parks are now common, but the need for mass transit to service them from suburban sprawl has not been addressed. In fact, there seems to be no simple way to handle this type of dispersed traffic pattern.

You answered your own question. It's true that telecommuting could handle some of that, but plenty of people will either have to or prefer going into an office. From what my friends say, working from when you have kids is pretty bad for your productivity, and some just find it difficult under any circumstances. If you live alone it can be pretty isolating. And my impression is that the bulk of the most recent office development outside the City has been either way, way out (dirt cheap) or in the satellite urban areas like Jersey City, Bridgeport or Stamford which have rail.