Apologies to any Americans reading but I can't imagine an American Civil War-based TW game any time soon.

All the existing titles run for hundreds of years, with lots of factions and (supposedly) dramatic innovations in technology that give one side or another an advantage. The ACW lasted half a decade, with only two principal antagonists and limited technological improvements: I don't see how it fits the bill, at all.
Hey, no apologies needed. I'm an American and I agree wholeheartedly.

the TW franchise is not well suited to modelling the American Civil War.

I think they run into issues trying to model the subjugation of the new world, and I don't think they could get any more 'modern' than that.

I'd rather they looked farther back into history for their next title.