One other thing before you cry Uncle at H2O in Fuel. Nitrogen transporters? Closed system pumping. May be time to build Fuels for ETOPS in water free enviros?
The 777, as the biggest twin, is exploring new territory wrt operating higher (and colder) for longer. So rather than making the fuel more expensive for everyone, why not identify a solution specifically for this type of operation? A new system requirement for extreme cold exposure is implied. That RR are now urgently taking this on board is a given. Other systems designers (certainly not just engine designers) should be equally diligent.