According to the much more knowledgeable nerds than me that populate the Airliners message boards, the 757 being brought back is basically a pipe dream (though a quite reasonable answer to the A321, to be fair). It seems there will never be a next generation 757 simply because the tools and assembly line for that model are long gone, and the cost of restarting the program would be far too high.
A clean-sheet replacement is what Boeing would need if they decide to end their 737-Max line (which is looking a more of a logical move by the week) and offer a worthy alternative to the NEO. A great many of the orders the Max has logged in only came to be because Airbus is sold out of NEOs for nearly a decade.
Both Boeing and its key supplier Spirit AeroSystems, which pretty much builds their 737 frames to nearly completion and ships them by train for final fitting, are in massive debt at the moment, which makes any prospect of a 757 relaunch a non-starter.
Boeing will not be allowed to collapse because it’s so big and emblematic in both the civilian and military markets in America, not to mention its formidable political lobbying in Washington. So it will come to either relinquishing more market share to
Airbus in the short to medium term, or launching an all-new narrowbody plane heavily subsidised by undoubtedly WTO-busting government grants. Which would be more likely than not if Trump wins office again.