I really like the concept so far.
My only two concerns are:
- The abstraction of production lines across the country - so industry isn't inclined to concentrate to key towns, ripe for bombing. I'd like to see a choice between spread-out, safer, but inefficient, industry vs concentrated, efficient, but vulnerable to attack, industry. Along with this, I'd have liked to have seen unit-types tied to factories (so if you found out where the enemy's tanks where being built, you could destroy those factories, or you could bomb the coast to destroy their shipbuilding).
The lack of stockpiling resources - I'd have liked to be able to stockpile lots of resources before the war, while my supply lines were safe, so I could last a bit longer once hostilities were declared, or in any brief moments where the enemy convoy-hunters are disrupted (for example).
However, overall, I think the system's looking great!