In 1998, just at the beginning of the current Yankees run, there were many ideas floated for a new ballpark. Most alternatives involved the Yanks leaving the Bronx to either Manhattan (their home for their first 22 years) or the New Jersey Meadowlands. This proposal was different in that it not only kept the team in the Bronx, but in Yankee Stadium.
The plan was floated by the Bronx Boro President Fernando Ferrer. It involved reintroducing many of the Stadium's classic features including the Frieze above the upper deck and the exterior facade.
An interesting feature that was eventually incorporated into the new Yankee Stadium is above. It seems to be quite similar to the "Great Hall" at the new park. Basically a glass wall which extends the concourse out onto what was then Ruppert Plaza.
The plan was never really accepted by the Yankees though. It never really got past the proposal stage. While its a shame the Yankees didn't stay in the original Stadium, at least they are still in the Bronx.
You can see these and more images of this proposal at StadiumPage.com.