Don't worry I promise I won't sue! :
One can only hope. And not wishing to convince myself on the obvious logic in doing this time period, the thing that always made me think a ACW game was beyond the scope of a total war game was that they liked to have a number of sides and just having " the blue" and "the grey" wouldn't really work on the campaign map side of things.
However I cold see a "colonial" time era where you have the great superpowers, Great Britain, France, Germany, USA, etc along with African nations ( Zulus, Africaan's ) then I think it could fit into the more typical total war game setting. In fact a dedicated ACW game could be done as an expansion, just concentrating on the ACW battles.