It's all conjecture. And for one thing, he doesn't take into account that if the Brits "respected boundaries" as he suggests, the rest of the continent probably would've been carved up into additional countries by Spain/Mexico and France, posing the eventuality of territorial wars. Once Europe started setting foot here, the Indians were goners one way or the other. An earlier end to the slavery issue is a wild guess. The only virtual certainty would be no NFL.
Even if there were an NFL* there would be no NE Patriots. Fair enough.
Counterfactuals do put one in mind of Avalon Hill games where WWI is breaking out and Mexico sides with Germany to get back Texas (etc.)
But reading the reasoning in the linked article puts another spin on the "confederate flag" issues elsewhere.
Whereas I am bitter that the southern states essentially fought a war for their "right" to keep slaves, it makes a certain amount of sense if they believed that is also why they fought against England. It puts an interesting new spin on their feeling of being betrayed, if the revolution was (for the Southern colonies) simply a means to an ends, that of perpetuating slavery.
I do think the Virginians (especially Jefferson) had at least ambivalent feelings about slavery, and Virginia was really the state that "counted" in the South. I put them in the column of "really did want this all-men-created-equal" concept... even if eventually that meant
all men, or worse yet, all people. IOW, I don't think the Virginians (probably) thought of "liberty" as meaning the right to hold slaves.
But when you get to the people whose great grandchildren wrote S.C.'s declaration of immediate causes for secession, it makes you think - to them, if an enormous part of their sympathies in leaving Britain were simply that it's better for slaveholders... suddenly their secession from the United States makes a great deal of sense; the abolition movement in their minds would constitute a betrayal.
The new piece here is the suggestion that perpetuating slavery in the American South might have been the whole
point of the revolution from the point of view of a landholder in a southern state.
PS, the Indians being "goners" seems different south of the border. Whatever the individual cases of cruelty were like under the Spanish and Portuguese, somehow the lineages seem to have mixed. Compare "Whites" in north America, and people from Spain and Portugal in the Iberian peninsula to today's population from Mexico south - the latter populations seem to have intermarried with the native Americans, not wiped them out.