If we're including hypotheticals, Brooklyn-Queens Connector?To expand on my earlier posts mentioning transportation, here are all the transportation options available to the Prince Etihad Fantasy Island Bridge:
SUBWAY
7 Train: Hunters Point Ave. & Vernon / Jackson
G Train: 21st St. / Van Alst & Greenpoint Ave.
LIRR
Hunterspoint Avenue
Long Island City
METRO NORTH (with bonus HYPOTHETICAL)
Metro North to Grand Central, transfer to the 7 train. If the MTA got creative, the Metro North could take the Amtrak line over the Hell Gate Bridge into Queens, connect to the LIRR track and stop at the Hunterspoint Ave. station, and then backtrack to the East Side Access tunnel to terminate at Grand Central Station. However, it seems much more reasonable to simply take the Metro North to Grand Central and then transfer to the 7, so this isn't very likely.
CAR
The Long Island Expressway effectively terminates at the stadium site as it enters the Queens Midtown Tunnel.
McGuinness Blvd. services points south into Brooklyn.
Jackson Ave. services points north and east into Queens.
QMT services Manhattan.
FERRY
Ferries from Manhattan and the Brooklyn waterfront stop at Hunters Point South Park.
Ferry from the Queens waterfront stops at Gantry Plaza State Park.
HYPERLOOP (HYPOTHETICAL)
Hey, if Elon wants an NYC Hyperloop stop, it ain't gonna be in Manhattan. It'll be in Long Island City or the Sunnyside LIRR yards.
https://www.nycedc.com/project/brooklyn-queens-connector-bqx