It ain't broke, it's just outdated. The 737 will have to be replaced with a composites based aircraft. The immense success of the Dreamliner is proving that. The reduction in the complexity of building the fuselage will also mean more profit margin for these smaller aircraft.
The larger Dreamliner is being used to hone manufacturing methods, then they can be economically applied to the smaller aircraft. Boeing would be stupid not to have this conversation now.
OK, and thanks.