I've heard (can't confirm) - the old stadium stays....
That land can be your house. Think of the mansion you can build. LOL.
I'm not getting this design... have a go at it (bottom, number 4 pic at link).
Tradition and the look of old Yankee Stadium prior to its renovation in the 1970s will be incorporated into the new stadium. The new Yankee Stadium will seat approximately 51,800 fans. The main grandstand will consist of four levels that stretch from foul pole to foul pole, with nearly 30,000 seats in the first two levels. The third level will contain 60 luxury suites and the fourth level will be the upper deck. Additional seating will be beyond the outfield fence as it is today at Yankee Stadium. Many elements will be incorporated into the new stadium that were lost when Yankee Stadium was renovated in the 1970s. The stadium will be comprised of two separate structures: one, the exterior wall, constructed to replicate the original Yankee Stadium, built in 1923, and the other the interior stadium itself, rising over the top of the exterior. From the outside the structures will look like one building, almost identical in materials and design to the original stadium. The signature frieze, the lattice work that once rimmed the original stadium roof and was recreated in the outfield of the current stadium, will be added to the new stadium's roof. The famously cavernous concourses will give way to open spaces with sightlines to the field from nearly every vantage point. Monument park will be moved to a new location beyond the outfield fence once the new stadium opens. The new stadium will have the same dimensions and bullpen placements as the old Yankee Stadium had.
Ground breaking occurred on August 16, 2006 and the stadium will be completed in April 2009. The Yankees will finance the $800 million project, and the City of New York will spend $220 million for infrastructure and other improvements in the area. Most of the shell of Yankees Stadium along with the field will be preserved, and the city and state will help build a hotel, convention center, a high school for sports medicine and sports management, a museum and other offices in and around the current stadium.
http://www.ballparksofbaseball.com/future/YankeeStadiumII.htm
Here's more:
http://newyork.yankees.mlb.com/NASApp/mlb/news/article.jsp?ymd=20050615&content_id=1090587&vkey=news_nyy&fext=.jsp&c_id=nyy
http://www.ballparks.com/baseball/american/nyybpk.htm