That brings me too another idea: can other resources be made eshaustible, the way slaves are in RTW? That would be very good for modeling antother aspect of AOE.
I am almost certain they can be made so, how the game would handle this, I'm not entirely sure. This might make the end game a little tedious though, if one Empire has failed to establish sufficient hegemony in the period where there are resources to finish off its enemies without them. I intend to make regions with trade resources more valuable in this mod, especially gold and silver.

On the subject of regions, I'm also contemplating the idea of having some region specific units like there were in M:TW. I always liked those. An example would be the holder of Laconia can recruit Spartan Hoplites - equivalent to standard Hoplites but obviously with better morale and attack strength.