It seems that now, Samsung has filed for a patent for transparent “sensor pads”. This will be alongside the edges of a smartphone and will be available as controls in seversl applications.
The most obvious use case, and possibly the inspiration behind the tech, is mobile gaming. Console controllers have had buttons on top, where they can be operated with the index fingers.
Other suggestion could be the camera controls are the other suggested use of the sensor pads and Samsung may be on to something here. Moving all of the functionality away from the display, which acts as a viewfinder, will allow for more precise framing, unhindered by all the toggles and shortcuts, while still allowing plenty of control.