It's pretty clever, unless you realize the people we want to put in those seats are actual humans, who might not be thrilled to be packed like a sardine, staring into the eyes of a stranger for hours at a time.
That is a bit more personal.
I was expecting a few inches shaved off the seat depth and came here to say 'every single time it's "most passengers won't notice a difference" and then fast forward 30 years and the cushions are 1.5" thick and everyone's basically standing up'
There could be a group of seats in this new configuration and a group in the current standard (everyone forward configuration).