A lot of people here are concerned about the transportation, which I get, but people are missing the big part of this: the court's ruling is that the land can be used ONLY as a stadium. Unless there's a reversal (which the DeBlasio refusal to join in the appeal suggests is unlikely), they either use that land for a new stadium or they lose out on ALL of their investment which is substantial.
So, what stadium are you going to build there? Mets, Yankees, Nets, NY Islanders, Giants, Jets, and Red Bulls all have new stadiums there. The Knicks and Rangers just re-did MSG and aren't moving. Who's left? New York City F.C. (I mean, I guess you could also say the Cosmos, but there's no way they beat out NYCFC or have the funds required to do this).
For the first time, NYCFC finds itself in a position of LEVERAGE. Unless DeBlasio and these developers are cool on missing out on affordable housing/lots of money/development etc. etc. they HAVE to deal with NYCFC. They have NO OTHER CHOICE. The City has invested $400 Million ALREADY. The local councilwoman is already trying to make a deal happen as the nasty work of dislocation has already been done so the hard political legwork has been largely pre-done (I'll pause here to note that this was probably a stupid idea for the City to start with, and forced displacement for stadiums/malls is a terrible thing. I don't want to condone this nonsense, but only to point out that the usual fight over buying residents out/eminent domain isn't as present as it would be anywhere else, which is no small thing as NYCFC found out with the elevator company near Yankee Stadium).
This is a win for everyone: DeBlasio gets to say he rescued a terrible deal of predecessor and turned it into affordable housing. The developers get to rescue one of their projects. NYC gets a stadium deal with the probably the best terms it will EVER get.