I think I would add another deck - so it would be a double decker, but still have the bubble on top.
then again, it would probably need 4 of the RR 777 Engines and a wing span about the same as the B52!
I would like to see a plug(s) installed after the hump to make it longer and sleeker looking. Long and narrow would be more fuel wise also. With the longer plane, they could raise the landing gear to install 4 lower thrust versions of the 777 engines. I think it would come out looking like the old DC-8 super 63 with the CMF engine change. Now that was one pretty plane.
I do not think it would be cost efficient for Boing to spend billions on a totally new double deck body to out-do Airbus at this point in the economy.