Well, axis, I agree it would prove for longer campaigns, which in turn would allow an 8 victory city game to become more viable.
Also, I know it changes the odds a lot (if you take England and don’t leave a garrison, it automatically reverts to freedom) which is why I also had the other option which stated that if you were just one man short of your garrison requirements, then there was one chance in six, per round, that it would revolt and revert to it’s original nationality.
So, let’s say you have the 3 armor, aa gun and IC, then there would be a 1 in 6 chance, each round, until you get the appropriately sized garrison that it would return to normal. I think this option is actually the easiest of the options since you don’t have to calculate anything. You occupy territory X then you need Y number of units equal to X IPC value. If you don’t have that many units, then a die is cast (1 in 6, just like an AA Gun) to see if X liberates itself.
The die would have to be cast after the turn of the occupier, just to make it easy to remember, I’d say right before collect income.
Also, since Germany/Russia usually don’t have a lot of territories without the number of units needed, it’s not going to take that much longer. Africa would be an issue, is it worth 9 infantry to keep it pacified?