There’s also Remix OS for mobile coming. It has ability to connect smartphone to external display and work as on desktop. Old idea, but in that case it can work IMO.
Remix OS is simply Android ROM but adapted to use as desktop like OS. Of course it will only be useful for basic tasks like office suite work, browsing, writing, watching videos. And let’s get serious, no one will ever use their phone as PC, if we could to get PC spec in phone form factor it could work in way that phone is “computation module” for PC if it’s get connected to external docking station or display.