I'll give it a go and re-post some ideas here, some ideas, probably same as what you have already thought of, but like...
internal war, like say syria and and iraq internal militants fighting to take over a province. show shifts in area allegiance.
weather disasters, like say hurricanes, or earthquakes that take out some populated areas. this should affect industries and facilities, like say 30% loss in manufacturing ability for 5-10 years until replaced.
Though of course the problem with my idea may be that time in the game is too short. If i wait 10 years to have a massive rebuild on a manufacturing facility, that may have me wait all of 10-20 minutes? Or less.
Which is not really the effect i was hoping for. I was hoping the shifts of circumstance would change the landscape of the game for an entire game. Which if we look at real shifts in population or disease, or migration, or technology, or new housing areas, or new manufacturing... is only going to take a few minutes, hardly the game altering shifts i was hoping for from game to game.
So maybe this isn't really possible, unless someone can think of something i am not seeing.
Idea comes to me to slow down time, dramatically. But then there is too much in the game depending on how it is paced right now. So maybe it was a not well thought out idea. Or something that would have needed to be done when it was designed, so everything else could be fit in with it in a balanced way.
Anyway, thanks for the note back, but well... looks like a no go.