Since the root cause of most the 737Max related problems originate from trying to fit bigger diameter engines under low wings, I was wondering would it be easier for Boeing (from a technical perspective) to base the MAX on a 757 platform instead of 737.
Hundreds of thousands of people that asked that question. Excerpts from article posted on Feb 17, 2015https://aviationweek.com/commercial-aviation/boeing-sees-no-business-case-757-max
The 757 replacement question has become an increasingly hot topic, particularly since Airbus upped the ante by launching the long-range A321neo LR variant in mid-January. Commenting on speculation about a re-engined 757, on Feb. 11
, Boeing Commercial Marketing Vice President Randy Tinseth says, “The fact is, there’s absolutely no business case to support that.
We’re very happy with our 737 and 787 product lineups. So we’re studying the space in between them. Customer feedback has led us to look at an airplane that is larger than today’s 737 and has greater range than the 757.”
If the MAX debacle gets considerably worse, Boeing has only three logical choices and they are all desperation
(1) Resurrect the B767-300ER, and that is only because they are still producing freight versions.
(2) Resurrect the B737-800
(3) Make some radical improvement on the B787-8 to make it easier to produce and cheaper to operate.
At the end of the day while the 757 is an amazing airplane and will be missed I think you are taking its capabilities too far and thinking it is the ultimate airplane where as its corner in the market is being cannibalized by more modern aircraft.
An A321neo has an operating empty weight of 110,500 lbs, whereas a B757-200/300 has an OEW of 128,840 lb / 141,860 lbs. That's a considerable difference that comes right off the bottom line.