This does raise an interesting suggestion, though; suppose there could be, in the game code itself, an event that fires that makes occupied territories fill with insurgents (or whatever term is used) as an enemy army comes closer (say, one province away)? That would be cool.
I would be extremely dissapointed if there was no corelation between partisan activity and coming frontline.
One of the most silly elements of HoI2 partisan system was randomness of partisan pop-ups. There was logic behind general partisan levels (depending on terrain, historical reasons, number of occupation troops and such), but otherwise, partisans were just dumb rebels of EU - they were just randomly taking over the provinces, being silly annoyance instead of interesting feature.
What was made good in HoI2 (at least early on, later it was too much nerfed to serve the purpose), was TC penalty from partisans, which actually made sense and represented what resistance was most of the time all about - leeching out enemy supplies.
In HoI3 there won't be TC, but I sincirely hope rebel pop-ups won't be the only thing that partisans can do. Partial effects, like sabotaging industry/resource gathering, supporting intel of allied foreign countries, imparing supply lines or simply focusing on reinforcing themselves before launching something bigger is what is needed for such system to work, not more random pop-ups with fancy partisan-types attached to the unit.
While EU3:IN system of "rebels with a cause" is a good starter here, it's nowhere close to the good representation of WWII resistance, where taking over vast territories was rather rare (it happened, but was rare nonetheless), while other forms of rebelling were very, very common.