The 767-200ER has not been discontinued! It is there if anyone wants it. Of course the 757-200ERX will have a lower operating cost (Lets use our heads, whats cheaper to operate, a widebody, or a narrowbody.) The 757-200ERX is going to operate in a niche market, from smaller city's (that cannot support a 767 or A330) to mainly Europe.
"In my opinion this will result one of the major advancements in the air travel economics in this decade."
See how economical it is to operate a 757, let's say JFK-CDG. It would not be economical to operate a narrowbody aircraft from large point to point destinations, as cargo is a big factor in profit. Also, to answer TEDSKIS question as to why Boeing would even think of airlines operate an "uncomfortable" narrowbody on such long-range routes, well, I don't think Boeing or any aircraft manufacturer really cares what people think (even though I would not mind hopping the pond on a 757). Boeing cares about what airlines want, and airlines want $, which this aircraft would provide on thin, long-range routes.