The next election concievably could be a 4 way race. Establishment repub and dim as well as Trump and sanders as independents.
I have been posting since 2012 that 2016 would closely resemble 1860, with four major tickets. Neither party can swallow their populist alternative - Sanders and Trump. If, somehow, Hillary is denied the nomination she will run with Jeb Bush in a replay of Bell-Everett. Trump will be expelled from the GOP process as soon as he wins the first primary.
I've also posted the many differences between Trump and Perot.