Was anyone else reminded of this one?:
Flaws in the Airbus design are the infrastructure to lift the passenger cabin off and on, plus the loss of strength in the pressure hull. If, however, the aircraft had a fuselage along the lines of the CL44 or a 747 freighter, a lightweight passenger cabin could be slid in from the front or back with much simpler ground handling equipment. The pressure hull would only have to open at an end, rather than along the whole length. The only real downsides would be the extra weight of the inner cabin and that emergency exits would need an inner and outer door.