The next big steps that CA need to make in the next Total War game needs to come from a switch to DX10 and some proper multi-core support. With those changes there would be a substantial improvement in the quality of the eye candy, both in the individual units themselves and their environments, and also from the potential scale of the battles. The era is a tricky thing, but to be honest I'd be happy if they just continue to refine the Medieval setting. It's the best one and the only one that really works in my opinion. What makes the Total War games so compelling is the melee fighting, when your horde of little knights and peasants runs screaming into somebody elses horde of knights and peasants to stab their faces off. With that reduced to just the Napoleonic exchanges of musketry and bayonet prodding I don't think it'd be too exciting.