Not sure if any airlines have figured this out yet. But there can be a good compromise. The hardshell can be modify to just move the head back (not the entire seat) and then the bottom sliding forward, so at least your chin is not stuck against your chest. Also, add an "air cushion" that pushes the seat cushion forward to give some lumbar support as your bottom slides forward, to give a true angle from head to toe. I think this small change will make those Y seats that much better and minimize intrusion to the person behind you.

As for other improvements, let's be real, it's Y class, can't expect too much luxury.