787 displays GPS alt on the on the PFD altimeter tapes if pressure altitude is lost - maybe the 777 software update will do just that?
(just like the 787 will also display airspeed computed from AOA on the PFD if pitot static is lost, and standby attitude and heading is also displayed on PFD when needed).
The 787 setup makes perfect sense to me. It's futile to think "what if in the past we had X", but this could probably have saved some lives.