Donald Trump (R-NY)/Scott Walker (R-WI): 272 EVs, 50.2%
Hillary Clinton (D-NY)/Elizabeth Warren (D-MA): 266 EVs, 49%
Not likely, but possible. A little unorthodox, but maybe Hillary focuses on courting hispanics and women so much that she loses whites nearly 2-1.
Also the Clinton/Warren likely disaster is amplified when Trump chooses "reasonable" Walker, enabling him to win WI, MN, and MI by razor-thin margins.
This Rust Belt thing is probably going to happen, it has been a long time coming and Trump knows it. If Hillary wins, 2018 will be the biggest midterm route in history, which is amazing considering we just came off 2010 & 2014.