The Motorola One Action has finally been unveiled. Like most of its siblings, it has a 21:9 screen and mid-range specs. However, it sets itself apart with its "industry first" wide-angle rear camera, which allows for the capture of landscape video while the phone itself is in portrait mode.
https://www.notebookcheck.net/Motorola-One-Action-launches-with-groundbreaking-rotated-wide-angle-camera-sensor.430862.0.html
Such a rotating cameras also for main sensors would solve a lot of vertical videos, wanted or unwanted. With 21:9 coming it would be about the time others also made some countermeasure against 9:21 videos and pics.