I think the problem for both Airbus and Boeing is that if they make a 737-a320 replacement big/heavy enough to also replace the 757-762-A300-A310 in the 200-260 short/medium range segment, a shrink to cover 150 seats will become too heavy to compete effectively with stretched, lean CSeries variants optimized for 130-160 seats and possibly Embraer.
So I expected a bigger wing and engine for the A320, A321 and possibly longer stretches to cover >170 seats and higher payload/range and a new design smaller and lighter then the 737/A320 to compete effectively in the huge 130-170 seat short/medium range segment.. Flights longer then 2000nm/4 hrs are really a niche globally..
