As detailed in early November in my post Did We Learn Anything: Carry Trade Edition:
The issue is that at some point the dollar will stabilize (or gain in value), increasing the "real" cost of borrowing the dollar.
BUT... if the correlation of assets purchased is near one on the way up, it is sure as hell going to be that high or higher on the way down. And what happens to all these investors that are attempting to leave the same exit door at the same time? Massive re-purchasing of the dollar and massive selling of any risk asset... joy.