Real estate can also be a hedge against inflation. One alternative to the housing bubble is that inflation is much higher than reported and the market is responding accordingly.
If the dollar does lose 90% of its value over the next ten years, then that $600k loan becomes a $60k loan in today's dollars.
Mexico occassionally devalues its currency. Rumors are that the officials in the know take out huge loans in Mexican Pesos, convert the loan to USD, then pay the loan back after the devaluation.