Boeing will start deliveries of a new airplane in 2020 called 777z for now. It will be 12% more fuel efficient than its competition and will bring huge savings to airlines in reduced fuel costs. The plane itself is based on Boeing's 777 airliner.
The new 777x will use the GE9X engine from GE Aviation and will have composite wings that are longer than the ones on the current 777. With longer wings, the plane gains improved efficiency, but it also adds a problem for negotiating airports. But its wings aren't just long. They fold up when the plane is on the ground, shortening the wingspan by 6 meters.
Boeing has received 259 orders for the airplane already.