The effectiveness of firepower and its accuracy at varying ranges, plus the effects of cavalry and artillery, add in a splash of misconceptions, and you have some serious balancing problems for the Napoleonic era. It would be difficult to effectively simulate any game with the Total War engine in an era where seeing a target means hitting a target, so World War games are unlikely. I'm not so sure most Total War fans would take to a fantasy game, or that CA could compete with the LOTR games. An early gunpowder game, say 1450-1700, might work well with the engine. A "Shogun II" or a "Medieval II" might not be entirely out of the question either.