So I came across a concept video for iPhone 7, but it's just a concept and there is no reason it couldn't be considered for any smartphone. In fact, if it's even possible, we'd probably see it on Android first. 
Here's the video:
What do you guys think? I think the idea is pretty cool, myself. With flexible screen technology already starting to see the light of day, do you think something like this is feasible? I image that it would start out as more of a manual thing; IE: You pull the extended display out yourself and push it back in, maybe out one side of the device. But it would be sort of a best of both worlds situation. Bigger screen for gaming or watching movies, then back to a normal pocket sized phone when you're finished.

Here's the video:
What do you guys think? I think the idea is pretty cool, myself. With flexible screen technology already starting to see the light of day, do you think something like this is feasible? I image that it would start out as more of a manual thing; IE: You pull the extended display out yourself and push it back in, maybe out one side of the device. But it would be sort of a best of both worlds situation. Bigger screen for gaming or watching movies, then back to a normal pocket sized phone when you're finished.