So... if you are prosecuting a war, you should have to leave the entire rest of your empire defenseless, so that anyone else who chooses can invade me and pillage and burn my empire at will, and capture multiple cities?
Cities are being designed to defend themselves, but I don't think they're being designed to be able to hold out alone against multiple units, or to prevent field pillaging.
You really think if I have say 8 cities, that it will be unplayable with 1Upt for me to have say 25 units? Say, a 4 ship navy, a 6 unit empire defensive reserve, and a 15 unit invasion army with 3 siege units, 2 archers, 3 cavalry, 3 spearmen and 4 swordsmen?
That still feels low to me, but is over 50% more than your 16 unit example.
I sure hope you couldn't support that with 8 cities. Maybe if that was all you were doing with those 8 cities (supporting units), or if you cut all those numbers in 1/2
so say 12 units (3 reserve, 2-3 ships, Siege, Archer, 2 Cavalry, Spear, 2 Swords)
Sure, but that's a gold cost, not something that your cities will have to be "building" instead of units. I don't think there is any evidence that cities will spend most of their time building structurse.
They didn't say it was a gold cost...they just said it was a cost (it was a gold cost only in Civ 4... and that was good because it was delocalized... but in civ 1-3 it was production from the 'home city'... good to get rid of the home city idea, but gold for the military diluted a military playstyle... except for the fact that maintenance was pretty insignificant compared to build cost.)
If you are playing in a military style, a significant portion of your economy should be going towards your units
In previous civs that meant you had them Building units.
If they want a smaller number of units, that don't die often, then you won't be building units, instead you will be maintaining/reparing/upgrading them.
In Civ 4 terms, with gold as the support
I would imagine that units might cost almost as much maintenance as they do production... ie a 15 hammer warrior cost say 3 gpt to maintain. (and something like 45 gold to completerly repair from 1 hp)
This means that you would have maybe one city that Produces the occasional unit*... but multiple cities that don't produce anything instead they work cottages to maintain the units you have.
As well as cities contrbuting to the civilian portion of your economy (tech, government expenses, culture, buildings, etc.)
* indeed 'producing' units might be out altogether, you might just Buy units with the same resources you use to maintain them. (that would work for how to deal with a city building units when a unit is there... you can only buy a unit when one is not there...but you can't move it till next turn... so you can only build 1 unit/city/turn.. but that would probably be more than you could afford unless you'd spent a lot of time without units.) Make it so that units have Building Prerequisites (ie you can only buy a Tank if there is an expensive Factory there) and you have about the same system.
I could see it becoming so that
Production->Development resource.. can get turned into gold
Gold->Military Resource... can get turned into production, in a limited sense
Science (separate from gold)->..tech resource
Culture...another separate resource... possibly competing with Science (provided by 'elites')..-> Great People, Borders, New Social Policies, stopping 'resistance' from appearing through Happiness.