While Civil war alt-history isn't a new fiction trope recently a book, Underground Airlines, that did a pretty bang up job of tackling the subject feat. an undercover black runaway slave capturer forced to work in the 'free' north . The south was pretty dystopic (similar to Handmaid's tale) and the books critique of the what would be considered northern liberal based racism was spot on so it could be done.

Only thing is that while the GOT showrunners seem to have a great handle on complex plotting and quippy dialogue, they also have a vulgar pornographic side. Plus no one wants to see GOT's "Evil/Good are rarely black and white, but usually grey" character work applied to modern slavery.