I dunno but the CEO of Ryanair is on the radio saying that he is talking to Boeing about this very arrangement for his 73's.
Apparently he wants some stools or something for such pax to "lean on" instead of the standard seating. They are talking of replacing the back 12 seats for this arrangement. These travellers would also fly free. I assume however that their baggage would fly for a huge fee as they would get to lie down...