Stan,
It certainly is possible Argentina may default and the government has not learned, yet I do not think it will be anything as bad as 2001 and I also believe that with the vast natural resources etc, the next government after Cristina fails and is out will do things right.
Even so, if there is crash, I do not think real estate will fall much if anything because people do not trust banks and real estate has been there mechanism of saving in dollars. It is real property. Selling and getting your money out could have been a problem but I think if you have an income in dollars from investments, pensions, business etc, your costs of living will only go down not up. The people earning and making pesos will suffer but it will become cheaper for dollar incomes.
That said, I think people wanting to live in BA may have a second bite at the apple because things are not as they were in 2002-2005 but it may get cheaper for expats.