How would this scenario play out: Democrats nominate Sanders in 2020, traditional Republican voters abandon Trump for Haley in the primaries, and Trump runs for re-election, on his own, without a party in 2020.
I'm thinking that Haley, as the official GOP nominee, would possibly become the choice of the vast majority of Republicans, while also garnering lots of Romney-Clinton white collar independent voters and leaving the Obama-Trump blue collar independent voters to choose between Trump and Sanders. Sanders of course wins the Democratic base, minus the neoliberals who flirt with Haley.
Here's one possible map that shows how Haley could win. The normal Republican states in the South and West vote for Haley and give Trump little to no support. The very liberal states vote Democratic and conservative voters split between Trump and Haley. Appalachia gives plurality victories to Trump. Haley wins plurality victories in VA, CO, PA, NJ, NH, and MN by winning massively among college whites and upscale non-whites. In NJ and MN, she wins only 35% of the vote, but it's a winner take all system.
Haley/Rubio: 277 electoral votesSanders/Harris: 209 electoral votesTrump/Pence: 52 electoral votesPlease post your own possible outcomes.