It rarely pays to disagree with Sowell. Nevertheless, it's way too early to feel all this doom and gloom. He reads like George Will in this case. Since it's unlikely that Trump or clinton will fail to reach 270 electoral votes, why try to predict a Trump disaster?
No one knows what Trump would do in any hypothetical circumstance. Likely,Trump doesn't know. It's hard to believe he could be worse for the good guys than obama who worked with purpose to make sure the good guys felt the convex side of the shovel with every decision. Trump might do some things good for American citizens occasionally, maybe by accident.
Most DC denizens these days say and do things every day that harm American citizens.
The thing that Sowell has joined most pundits in explaining, or not explaining, is that the composite DC "leader" made Trump possible, gave us Trump as a gift and made it so vast numbers of American people will grab for someone, anyone, who claims to be apolitical. Give us a President who will do the occasional right thing, even if he stumbles into it.
At least Sowell didn't say clinton is to be preferred.