Ther you go, my friend! The 757-400 has alot more potential than you all think! Look at how successful the old -200 is, if Boeing gives a plane like that newer aviaonics and gives it better range, plus adds a cockpit like the 777's, it will sell like hotcakes. That is one of the best ideas Boeing has had in a while. So what if we go back to DC-8 and 707 days? Hell, those were the best aircraft you could fly on! Whether the aircraft is a wide body of narrow body, it makes no difference, it's still a plane, and it still flies. Plus, the added fuel will add MUCH more range that 250-nm, more like 1,000 or so.
Guys, you're looking at the future of aviation. The 757-200X, if launched, would still be around in 2040. Production would end in about 2020. This aircraft will be something great, just wait and see.