I think the wingspans of the aircraft you mention are interresting but not really relevant. I meant that the "smaller" wide bodies like the A330 and 787 that can fly medium ranges and are 757/767 options have wings spans around 60 meters.
Indeed. In fact, they all have wingspans exceeding the 59,6 m wingspan of Boeing 747.
My point is that there are large numbers of airplanes with wingspan in the range of 43 to 52 m. Calling the list again, the classical longhaul narrowbodies B-707, DC-8, VC-10 and small widebodies DC-10, Tristar, A300, A310, B767, MD11 and Il-86. All of those are meant for category D gates. Boeing 747 was the only aircraft bigger than category D till A340 came out.
Would 3 abreast, 2-1 seating on a narrowbody make a nice first class?