This is my dream scenario, but you underestimate the powerful effect that incumbency will have on Trump's chances.
I don't underestimate it but it's also by no means insurmountable. Given all the potential scandals, given his instability, given the possibility that they'll be another economic collapse I think he could very easily lose. Warren would be the perfect candidate to beat him too. She's politically pretty close to Bernie but isn't as polarizing a figure and could appeal to Hillary supporters as well and she'd also do a great job of calling out Trump's phony populism by pointing to all his Wall Street appointments. Trump winning had as much to do with Hillary being a highly flawed candidate as anything and even then he still lost the popular vote.
