I know a lot of us remember killing the spit factory in AW, and it shows up regularly as a wish here on the wishlist. I have heard the arguments about why a static *Insert Plane Type Here" factory would be a bad idea in AH and generally agree with that line of thinking. However, I do like the idea of strategic bombing affecting a country's equipment availability and had an idea of how to do it.
Instead of making a factory a place on the map like the troop training or AAA factory, make it part of a town at an airfield. Make the factory detectable only by a passover of the town by a designated recon bird. Once the recon bird successfully returns to base (to simulate developing / analyzing the photos that were taken on the mission), the factory appears on the map in some way. Until the recon bird returns to base, nobody knows where the factory is (maybe including your own side to prevent spying!). This would open up the world of reconnaissance. Imagine if only an unarmed recon bird could locate the spit 8/16 or the La-7 factory deep in enemy territory.
Once the factory gets detected, a heavy mission (something along the lines of what it takes to kill HQ) can destroy the factory. No more of whatever that factory was producing for 20 - 30 minutes. Here's the fun part: after the down time, the factory starts operating again at a new and unknown location. It would start the entire cycle of finding and destroying the factory all over.
There would need to be some coad to keep a outnumbered country down to its last few bases from suffering the penalty of having their factory visible as soon as it's up. All stuff for greater minds than mine to take on!
Regards,
Hammer