galaxy flyer
Quads have to flight plan accounting for depressurization at the ETP, so it shouldn't be an issue. I agree ETOPS has, and will, improve reliability and safety for quads--better fire suppression, ETOPS=qualified engines and accessories, avionics cooling, etc. But, since twins HAVE to land at the nearest suitable airport in the event of engine failure, why are we extending that restriction to quads? They have demonstrated many times, that if planned correctly, can safety continue after an engine failure to the destination or a better alternate, esp. on trans-polar, trans-Siberian, and some oceanic routes.
I am not sure if most of the airlines consider depressurization at the ETP. I am under the impression that ETP fuel is calculated based on an engine out. So most of the flight plans for A340/747/A380 would be based around 20, 000 ft (1 eng inop level off) rather than 10, 000 ft. (typical depressurization altitude unless extra oxygen).