Beginning April 12, 2014 - The northbound travel lanes on the Route 1&9 Pulaski Skyway (heading toward the Holland Tunnel and New York City - from the direction of Newark) will be closed for approximately 24 months while the New Jersey Department of Transportation (NJDOT) rehabilitates the bridge deck.
My best guess is that something like 35 - 40% of the traffic between Newark and Manhattan uses the Skyway. I'd guess that less than 50% of traffic between Newark Airport and Manhattan uses the Lincoln Tunnel or George Washington Bridge and only a small amount of traffic uses the NJ Turnpike Hudson Bay Extension to the Holland Tunnel.
I suspect this will mean massive back-ups considering how bad it has been without any disruption.
Consider the train. AirTrain Newark / NJ Transit into New York Penn Station for $12.50 per adult passenger.