I think it all boils down to money.
While the city owns it, the Yankees could in fact buy it and could have kept it as a shrine.
However, with the price of real estate in NYC, the reality is that land better serves financially for other uses such as parking lot, etc.
To that, add the costs associated with maintaining it long term.
It is a shame and I can see trying to keep it for posterity given the history of this club but I can also see the financial argument and the thought of moving on to a new home, for a new history.
My last memory of the old stadium as I left the new stadium in May.