blended wing
boeing are working on blended wing technology,where the actaul wing tip twists to offset spanwise flow.this will compensate for winglets and weight.also to answer a previous quote about airbus having no vortex generators,i think if you look at the 747 wing and even the old sp its a hella of a lot cleaner than any bus wing .the bus has sh&t hanging out everywhere,lots of parasitic drag