The Britannia 757 seats are, in ways, similar to the new thin seats of which you speak.
They have thinned out the section of seat back at knee height, removed the seat pocket and moved the tray stowage to the top of the seat back. This has the effect of giving more "knee-room" whilst maintaining both the Pitch and the total capacity of the aircraft.
Its a far cry from luxury I can assure you but its a step in the right direction and those of us with longer femurs get a little bit of a break.