tdracer - I fully agree that it would need a brand new multimodel cocpit updated to modern standards and prepared for the future of more automation. The body sould also be a composite play like the 787.
However, using the 757 as a template would not only create a good looking plane, as some comments have agreed with, but probably shave a couple of years, and associated costs, of the development cycle by reusing some of the principals like aerodynamic shape and and landing gear. Something Boeing desperately needs at the moment.
Personally I don't agree with this trend for ever larger 737's for the bread and butter jobs of short haul flying. The 150 seat aircraft was a more versatile one that encouragede more direct routes and higher frequencies. However the larger planes have been encouraged by slot restrictions, airport fees and increasing pilot costs.