Most people will end up coming in from the northern end of Manhattan and parking above 60th, so really it’s a big win for the companies that own parking garages uptown. From LI they’ll come across the Triboro bridge or go across to the Bronx and come across one of the other freebie bridges up there - lots and lots of new traffic congestion as all those additional cars try to fit across already congested bridges. From NJ they’ll go up to the Geo Wash bridge and come across that way (they’ll be paying the toll for the bridge, but they’d be paying a toll anyways if they took the tunnels).
Then all of these people will crowd onto the subway uptown and take it downtown below 60th street.
So, lots of additional traffic congestion, lots of additional pollution from slow-moving cars, lots of additional subway riders, but very little additional revenue for the MTA.