Originally Posted by saturn

I agree on paper, having a common type 100-350 seats sounds brilliant.

Yet, don't know how you standardize two cockpits designed inherently different, with flight control laws and logic, electrical/hydraulic/pneumatic system components and logic, all different. Rockwell Collins vs Thales avionics displays & FMGCs, Auto-thrust vs throttle. And outside of the cockpit, the MX side has no commonality. You'd have to rip the entire brains and central nervous system out of the 220 and replace it with 1990s tech to accomplish what you seek. If SWA couldn't get the 737 classic the same type as the MAX, this will never happen.