I’m not an expert, but the 757 was a larger and heavier plane which changes the economics a lot. It also stopped production over a decade ago so restarting prod

I’m not an expert, but the 757 was a larger and heavier plane which changes the economics a lot. It also stopped production over a decade ago so restarting production would’ve been a challenge. On top of that as you said airlines wanted to maintain the 737 type rating so pilots didn’t need retraining. The 797/NMA program Boeing is proposing is a replacement for the aging 757 and 767 fleets.