That is the type of basic question that needs to be addressed, whether any combination of systems management would allow the aircraft as configured to fly the route that is projected.
Jonfra makes a case that the known onboard fuel would not support the flight path that is assumed, a path incidentally that requires active and skilled crew input. Boeing engineers have the best 777 knowledge, they could tell what endurance is possible given this path, but they have been entirely mute on this thread
afaik. The flight remains a mystery which erodes confidence in the integrity of the world civil aviation authorities.