Much as it would be cool to have a stadium in your backyard, which I fully approve of (and not at all picking on you,
DeGrozz), I just want to point out a few things about not having it in New York City.
You're basically going to lose all the New Yorkers if it's in Dobb's Ferry, say. For one, it's $20 round trip (off peak). So add $350 to the price of your season tickets. For another, for a 7pm match there's only three trains back to the city on a Saturday: 9:50, 10:16, 11:16, and on Sunday there's no 9:50 train. Can we fit 10,000 people going back home on that first train? Seems unlikely. Will they have crowd control to prevent pushing and shoving on the platform as folks fight to get on that first train? If you can't get on that first train on a Sunday you're gonna stand there for an hour until the next one.
Also, it's about a 40 minute train ride from Grand Central, so you'll be leaving work at 4pm if you need to take a subway to Grand Central and then get on the train. The other way, for that 7pm match you'll be getting back to Grand Central at 10:30 at the earliest, or 11pm if it's a Sunday. And then you'll be getting on the subway to get home.
Basically, the stadium has to be in the city, and it has to be near a mostly convenient subway station. If you have to take commuter rail to the stadium I could see easily 50% of the season ticket holders not renewing, but I'd bet it would be closer to 80%.