As a 747-400 pilot, I know that with loss of all 4 generators, I am down to battery power. Two batteries (main and APU) and two standby inverters and their respective AC standby busses power enough instruments and functions to land the airplane. The captain's PFD, ND, FMC will work. So will the left VHF radio, dome lights, nacelle anti-ice, and captain pitot heat. I can trim with the alternate trim switches. The landing gear release will work, and the gear will extend hydraulicaly. The flaps extend in primary hydraulic mode. Leading edge flaps extend with air mode. I can fly an ILS raw data approach. However, I'm limited to 30 minutes in this scenario, so being close to an airport when this happens is the key to success. Main problems besides the obvious are the loss of anti-skid braking and loss of thrust reverse. We practice loss of all 4 generators during initial simulator training.