So: If you were in Sully's position -- both donks failed and APU not running -- are you safe enough? Can you get us back on the ground?
Just to put this one to bed; Sully's flight had generators from both engines online until the moment of touchdown. Both engines were badly damaged but continued to generate above idle power (enough to keep the generators online and the aircraft fully powered both electrically and hydraulically). This was one of the reasons why the aircraft was able to stay in Normal Law until it touched down. If both engines had completely failed, the aircraft would have reverted to Direct Law.