Complete loss of controls is not only a problem for FBW (fly by wire) aircraft (like Airbus, B777 etc), but generally for all modern big jets. They all do not have a direct connection of the control surfaces and the cockpit, like the DC-10/MD-11, all Boeings, old A300/310. Remember that all lost-of-control-accidents happened to non-FBW so far (was the A300 in Bagdad a 600er?). When you loose all hydraulics, you also loose control. A tube full of oil is much more vulnerable than a branch of small cables, which you can route anywhere through the fuselage.
On the Airbus we train this "complete loss of control" to a certain extend. You still need the emergency generator for electricity and one hydraulic system. You can steer then with rudders, elevator trim and asymetrical trust. It can work with good team work. We managed it on try number one.
When all electricity is lost, then it is not possible to continue. I sometimes think about NEMPs (nuclear electro-magnetic impulses). Those would be the end for a FBW aircraft. But also for the rest of the world...
Dani