If he does all three of these things, he could win by Ralston's estimation. I do not think it is impossible for these things to happen or even unlikely. Trump very well may be holding a substantial portion of those 200,000 new registered voters in his back pocket. Ralston doesn't know if he has that or not. The public polling could also be right, which suggests Trump is winning Independents. It's just not as clear as Ralston makes it.

He noted that Trump would need 90% of his base, something he is achieving or coming close to as NeverTrumpers fade away. He also notes that Clinton would need to pull between 80 to 85% of her base. Alternatively, her base turnout could diminish by five to ten percent as compared to Republican turnout and it would have the same affect. Last, Trump would need to win Independents, presumably just get a little more than Clinton among Independents.

All of Ralston's analysis is based on traditional partisan assumptions. It's not clear that such assumptions will prove useful.