Assault Squad, Red Dragon and Company of hereos come to mind.

They don't have a world domination campaign though, just battles.

In the future I do see Sega doing more futuristic games, as it stands a lot of the mechanics for massive land creatures, flying units and spells can be used for a ww1 style game.

Though I don't know how the campaign map would be played out as not each nation in real life had the industrial output to pump out tanks and aircraft. Battles I feel would also be more prolonged. One battle could in itself be divided in half a dozen smaller battles.

AI needs to be improved by a lot though as the game mechanics expand so much.