None.
He either stayed the same or lost margins from Mitt Romney in states like CO, NV, NH, VA, and MN. They were only close because Hillary did awful compared to Obama. His only path to victory is a candidate as scandal-laden, unpopular, stiff, and polarizing as Hillary Clinton or a viable third party siphoning votes from the left.
I do believe Trump has no path without PA, WI, or MI, but your post is wrong. He reduced the democrat margin of victory in CO, NV, NH, and especially MN. Clinton was a bad candidate, but keeping your share of the vote roughly constant while third parties gain a significant chunk is still a swing towards you. Clinton got a lower share of the vote in 92 than Dukakis in 88 but it was undeniably still a swing to the democrats.
Once again, I'm seeing the assumption that all 2016 third party votes would go to the democrat in 2020, which is unrealistic and impossible to know at this point. It reminds me a lot of the assumption nearly every pundit made that, as more republicans dropped out in the primaries, all of their would be voters would coalesce behind a NeverTrump candidate, when Trump actually continued to gain as more dropped out and the "ceilings" drawn at 25% then 30% then 50% fell.
From what I've seen in polls, Trump has done a very poor job bringing back third party voters to him. Gary Johnson voters used to support Republicans by a 20 pt margin -- now it's about a 0 pt margin. Most third party voters still hate Trump.
From anecdotal experience, that's been mostly true too. Trump really hasn't improved his coalition at all. Plenty of people I know who voted him are kind of sick of him too.
