I was fiddling with an idea similar to this, albeit set 20-30 years earlier, just so it could cover the Crimean War, or Bismark's wars. It was just some personal test work, and I was importing models from the Blood and Iron mod, but encountered some troubles with shaders. I think it's certainly a doable thing, you'd just need to find period-appropriate uniforms for all the nations, and maybe do the heavier work of adding more factions. Blood and Iron also has some great animations, just some simple OpenBRF exporting and importing. Goodness, I'm suddenly reminded of that Schleswig War mod a while ago, shame it never panned out.... Anyways, all of this I tried some year or so ago. With the release of the Imperial Grandeur 1853: Total Conversion mod, you'd have even more access to later 19th-century uniforms.
Not quite the answer you're looking for, just some personal rambling, but again I think it's doable. Just a lot of dedication redoing all those uniforms and some other tweaking with factions and scening, but oh gosh are L'Aigle's models gorgeous. If only even a fraction of Warband mods had that much polish.