I think this a cool idea. I think piano needs its own version of the guitar tab to be more approachable. For someone who knows the basics, just seeing the chords goes a long way. But this gives better detail. One thing it glosses over is how the format responds to greater range. It acknowledges the fact that only 3 of piano's ~7 octaves are shown, but it doesn't address how much difficult it would be to read if there…
Ledger lines preserve the melodic contour but it's harder to read the notes. 8va's stay within the regular five lines you know how to read, but fragment the melodic curve. This way has the advantages of both the above and the disadvantage of neither.
(The lack of key sig in that image is a limitation of the software it was printed out from, I think; it should start in E and change around a bit afterwards. The "3"s are that software's way of printing tuplets.)