Maybe so, but a story like that depends on its variables doesn't it? There's a lot you can change that would either increase the robber-barons' hold (maybe leading to open revolt?) or prevent it from happening in the first place, or direct it in a different way. The way the history runs from an event could be quite interesting, and I'd say that, say, continued slavery in the way the above comic puts it is one of the least interesting results you could come up with.
Still, the idea of a strongly bigoted villain coming up with an utterly unexpected and (to them) unpalatable result to their time meddling, such as colour no longer being an issue but some different prejudice taking its place, remains an interesting one.