This is fantastic news!
As much as I enjoyed Shogun 2, the fact that all factions had near identical units limited some of the replayability for me.
My favourite thing about Rome was the variety.
March north and face the endless hordes of barbarians, make it far enough and face the chariots of Britannia or the heavy axemen of Germania.
Head south and face mighty Carthage, complete with war elephants and fast skirmishers.
East? The phalanxes of Greece and the pikemen of Macedon, further still for the heavy cavalry of the Selucids and if you make it to Egypt then watch out for the elite archers and chariots!
Absolutely brilliant game.
I am looking forward to the naval battles (ramming speed!) and the reintroduction of units like war dogs, flaming pigs, war elephants etc.
Good seiges would be nice, I didn't think they were great in Shogun 2. I need my catapults, ballista and battering rams complete with ladders and seige towers!