Here is a link to a story about a football stadium Mayor Bloomberg is behind. It makes sense to me. I think the Metro could double its attendance figures in NYC proper. http://www.worldstadiums.com/stadium_menu/stadium_news/general/articles/2002/art0039.shtml
Metro would not move to New York. Although Nick Sakiewicz did say in a chat a couple of weeks ago that they were looking at a SSS in NYC, it would be for an expansion team, not for Metro.