Megan,
Can you let us know why you think a depressurisation would definitely result in a ditching (whether ETOPS or not)?
Every flightplan has to take into account the worst case fuel scenario of normal cruise/OEI/OEI depressurised (if more critical than AEO depressurised) and use the most critical scenario as the minimum fuel uplift. So if there is a depressurisation, with or without an engine failure, right at the 5.5 hour point, then the aircraft will have enough fuel to make its ETOPS adequate airport.
So if fuel is no issue, what then is the reason behind your assertion?
Even the NTSB classified the damage to this B777 as 'light', so it can't be due to catastrophic damage - and a hole in the fuselage caused by an errant fan blade isn't necessarily going to bring down the aircraft (see UA811 where the entire forward cargo door came off, but it still landed safely).
Capt Fathom,
What would a B744 crew have had as choices if they were to suffer an uncontrollable fire at the CP between SYD and JNB, or EZE? No different to the modern twins really, is it?