I refer to the story in herald.net reporting from the Boeing Investor Day on May, 21st 2014. Reading the article we must come to the conclusion that a clean sheet design B757/767 successor will not happen for some time.
After the financial B787 debacle, which is now between $23 and $25 billion in the reds and with a costly B777X program ahead nobody in the Boeing upper management will have the will to try to sell another technical and financial adventure to the shareholders.
One could say that Boeing now has all the learning about how to develop and produce a fiber carbon aircraft and the development of the B777X wing would give further experience and would lower the risk. But this aircraft – a B757/767 successor – would have different competitors, coming partly from Boeing itself. The B737MAX-9 and the A321neo from the lower side, the B787-8 and a A330neo from the upper side. Of course, the B737MAX-9 and the A321neo would not be able to do the critical B757 missions and the A330neo and the B787-8 are optimized for longer ranges and thus would not offer optimized costs for, say, a 4000nm mission. But this market segment alone, which can not be served by the B737MAX-9 and the A321neo, would be too small to present a business case with another $10-$15 billion investment upfront.
Sales prices would also be a problem with a A330neo, which, with a 2018 EIS by 2025 could have written down development costs and could be given to customers for prices we see today for the baseline A330 (escalated by inflation, of course).
Boeing yesterday made clear (as Airbus did before) that future aircraft will (for the foreseeable future) only see incremental developments rather than revolutionary designs. The plans from Airbus for an electric regional aircraft might be the only exception, but we have to wait another few years to see if this concept will really become reality.
Is there a demand for a B757/B767 successor? Yes, of course! Will Boeing sell one aircraft less if they (and Airbus) don’t do it? No! And this is what counts for the shareholder. Period!