I think there are different approaches between A and B with A being in general terms-ire the 'model range' more inventive and innovative than B . But B have a slot of strength expecially in the WB market as the 777 is such a good platform. Also in Boeings favour is the 787 which is probably the most advanced airliner design around.
I think the big 'if' for Boeing is that should the 777-9X turn out to be a dog (a stretch too far) like the 737-9 then they really do have a problem because A will eat their lunch in the narrow body world for years because the 737 well past its sell by date . However if the stretch triple is a good performer then B will continue to have strong position in the long haul world.