The major hindrance I see to better and better PD (atleast at this point) is the way graphics are made-and that's something that may be nigh-impossible to get around. The ideal way to have the kind of PD I think we're talking about would be to draw units as separate from items(weapons and armor), and then item-types themselves, separate from size and quality. So, you could have Ermor invading a Hoburg province and equipping the little buggers with hoburg-sized iron cesti, etc. without having to draw 12 different types of hoburg/ermor units and then having to convince Johan K to raise the limit of units allowed in the game to 10 million

which, admittedly, is where I'd like it to be
