Hydraulic pump redundancy on the 787 comprises a mechanically driven pump on each engine, powering two separate hydraulic circuits. Each of these separate hydraulic systems also has an electric-motor-powered hydraulic pump connected to the aircraft's electrical system. There is also a third hydraulic system pressurised by two further electric-motor-powered hydraulic pumps. There are two generators on each engine and each of the four electrically driven hydraulic pumps is connected to a different engine driven generator bus. The third hydraulic system can also be pressurised by a pump driven directly by a RAT. (The RAT drives an electrical generator and a hydraulic pump)
Even with a double engine failure ('Sullenberger Scenario'?), electric power from the APU and/or battery should keep the hydraulic systems operational long enough to allow a 787 to descend from altitude to a forced landing/ditching or, hopefully, a suitable runway. Should the APU and battery system also fail, the RAT would provide hydraulic pressure to operate the aircraft's primary flight controls. Therefore, it seems there is a high level of redunancy built into the 787 insofar as the supply of hydraulic pressure to control surface actuators, etc, is concerned.
In addition to hydraulic pressure, actuators also need electrical signals to control their degree and rate of movement in response to pilot/autopilot inputs. After the recent electrical problems experienced by the 787, I wonder if the FAA are worried that, under certain electrical failure scenarios, some of these control signals may be lost due to fire.