The world of foldable smartphones will begin this year in a battle between Samsung and Huawei but the real champion would be Microsoft if it were able to strike lightning with the release of a Surface Phone that looks like this:
These photos are courtesy of LegsGoDigital that found a patent filed in 2017 by Intel that shows a phone-like device (a large phone, small tablet, or something new) that folds out into a large tablet, or more importantly, a PC. The single device would start off small and chunky, but would later fold out into a phone that is twice as wide (where you could have another app, chat app, calculator, live stats, etc) or into a larger almost 3-screen phone or tablet.
You can see here that some of the designs would be slick, especially if the bottom display that is touching the ground was disabled and so too the back display - it would be a built-in kickstand for your phone. I think we'd definitely need some super scratch resistant screens at that point, though.
Here you can see how such a smartphone would be.
Again, it could compete against Samsung's super-popular Galaxy Note 9 smartphone.