There is a massive psychological difference between operating a USAF UAV designed for 'Destruction of Things' versus having joe-public onboard a UAV Airliner operated by a Stanford MPL with zero Skin-In-The-Game, operating from a sweltering shipping container in a country with the worst labour laws. Oh wait, nobody anticipates that this will be the then next cost destruction frontier for airline CEO's.
The Boeing 777X (an Old Bird with New bolt-ons), was launched in November 2013 and will only be delivered in 2025 - Clean sheet designs are not in fashion for CEO's seeking short term KPI bonuses.