Google will never implement this feature willingly, considering it directly competes with their Android Auto, which they want to push as a default navigation app for everyone. They like collecting private information, and driving habits are so attractive to Google, they would be idiots to implement this feature and ruin the advantage their app has over other apps. It's not gonna happen, at least not up until they decide they have the absolute dominance with their Android Auto app, and don't feel other apps will be able to endanger that dominance anymore.
That being said, the only thing we can do is to modify the source code and change the display driver to invert the coordinates. It's a fairly easy task, but for someone who knows how to write such code. Here on xda I've seen a lot of smart people, capable of doing such stuff, so it puzzles me noone has took the opportunity to write it. I can only imagine there is something more to this feature than meets the eye. Until then, 2 mirrors in the car, under the windshield, can do the job.