> Another problem is that no matter how powerful a phone can be, it's still handicapped by its small screen real-estate.

With Windows Continuum, you plug an external monitor and a keyboard into your Windows 10 Phone. You get a desktop style experience on the big screen but you can continue to do phone stuff on the phone.

BUILD 2015 Continuum session - Windows Phone as a PC https://www.youtube.com/watch?v=FdzbXo38onQ

It becomes significantly interesting for the odd 4 billion people who will own a smartphone one day but may never own a laptop.

Toshiba tried something similar with a PocketPC (powered by Windows CE) a couple of decades ago, but it didn't work well enough to go anywhere.