Presumably, Snyder would show a cold opening at the beginning, set in Paris in 1783, and having somebody (maybe Vergennes?) give an exposition-heavy speech about how Britain won the Cape Colony from the Dutch, and that the Loyalists would be resettled there. As a bonus, he also mentions the eruption of Laki, and that a lot of Icelanders will also need to be relocated to the same area. Cue Hans Zimmer orchestra as a wide panning shot of a fleet of ships sailing to the Cape is shown, with some pictures of chained black people on said ships for the purposes of drama and foreshadowing.
The hard part comes in showing the intervening 158 years, to make sure that the audience is fully aware of things like the Dominion/Domination's taking on French and Southern US settlers, the purchase/capture of Portuguese and British colonies for fast expansion, and the rapid technological advancement brought on by free research grants.
So, yeah, I agree with Swiffness, a TV series would probably be better.