I've been through the foregoing discussion. Interesting ! There are some 1030 class 757 aircraft up there doing their job for the airlines day-in day-out and many of you confirm it's a fine aircraft. Why do you want to
replace those excellent workhorses, if there are other possible avenues ? ... such as eg cabin refurbish + engine change, to MAX (GTF PurePower or LEAP-X ? pending which may come up with an incremental power setting of 3,500 - 4,000 lbf beyond what is presently planned for A321) ? :
http://media.wix.com/ugd/4f7666_6da4...%2Bniche-1.pdf