Here in NJ, they wanted to build another tunnel under the Hudson River until the great Chris Christie pointed out that there was nobody to use it; the jobs in NYC, and the taxpayers of northern NJ, were melting away. People I know who commute into the city say there are a lot less people on the existing trains...
FWIW, the folks I know in Jersey who do commute to NYC, have always said, they would despise the trains, they will drive, deal with traffic and all that, rather then ride the train in. Some of them actually would rather cab it then ride in, that says alot.