Wow, I hadn't really thought about you being able to control the display. That could give us ebooks that follow you. What a cool idea! Whether it's on the back of your hand (
https://www.mobileread.com/forums/showthread.php?t=5055) or on the ceiling or wall or floor, or cereal box, no matter where you are or how bad your vision is, you can read the next page of your book.
Or for the teen, imagine if they had some kind of remote payer controls built into their hands or a glove. No matter where they went, they could continue to play their favorite video game against some favorite opponent across the country or across the world.
With all the cool advances in technology, I guess sometimes it's easy to forget how limiting the current and upcoming technologies are compared to what "could" be in the far-ahead future some day!