'everybody has known that the U.S. is on an unsustainable spending curve due to entitlements'

I wouldn't agree with that. I would say that the problem is fighting two un-funded wars coupled with a decrease in revenues caused by the Bush Tax Cuts. Long term we have issues with popular entitlements such as SS and Medicare. But our immediate problems are generally due to the drop in revenues from the Bush era and an massive increase in military spending.