Does anyone know if there will be an attempt to use these 777s on particular routes wherever possible, or will it be random?

It's been stated a number of 747s will be staying until 2023. Now considering that G-ZZZ aircraft were delivered 1995/6, and the last 747s in 98/99 I really hope there are yet to be revealed plans to roll this out further in the future.

Something has got to happen!