As we all know that the diameters of the 737 fuselage and the 777 engine are about the same, all we need to do to get the first single engined airliner is this:
Benefits:
* instant take off performance for the hasty traveller and taxi way users
* advanced bird strike evasion with thrust vectoring
* improved weight capacity at the front desk
* a tool for impressive circular momentum demonstrations
Sorry that I was bored...
;-)