Dear Jack, will there be the 'area of recruitment' system?
If a player captures a Greek province as Egypt or Carthage, he should be able to recruit Greek units from the cities instead of hiring them out as mercenaries. If he takes Londinium as Carthage, he should be able to recruit all barbarian units that barbarian factions can have (except some special elites).
This 'area of recruitment' worked out very nicely in Empire, where you could recruit local units wherever you went. Sail to India and we get Sepoys and Gurkhas, go in north America and you can recruit native tribes into the army. And what was good that it was a professional army system, not mercenaries. It had been in mods ever since good ol' RTW came out.
In fact it has been present in nearly all games from RTW to Napoleon. It was just not in proper form except for Empire. And even in Empire there were some restricted units.
And I would like to see it again.