That is the Reuters article, and another websites referal to it, I looked at wen when this was discussed on the "Boeing to cut 10%" thread.
"Any replacement would have slightly more range and seats, with one source nicknaming it “757-Plus” " was seen to be a reference to that 757-Plus was an internal workname used in Boeing.
There is more to this than can just be brushed off due to missing tooling. It can't all have been lost. The plane is still flying and one can still get spares. You can be sure the plans haven't gone missing.
The 767 is a widebody and can never be a quick and oversized fit straight into the airport parking spaces own stairs no belly containers 737 ExMax replacement. The 757 with a bit of more modern, economically optimized manufacturing, lighter composits and modern methoods of glueing and the latest most fuel efficient engines can. And the engines will fit actually under the wings. Also rumoured it can take off sanz tail scraping even without landing gear trickery.
Boeing don't need a mid market replacement. It has the 787. What it needs is a bread and butter plane it can sell and make in big volumes, within 3 to 4 years. Hopefully start preselling in 2 when the market comes back. Then having a tried and tested starter to modify speeds up the process.