It would happen, there would be opps for arbitrage to keep the offline markets roughly in sync.
Much like traders crossing the continent hundreds of years ago I imagine.
The problem with that is that there is no tangible value nor real inherent value to bitcoin other than as an arbitrary storage of said value (catch 22). This is why I'm confused a bit about where the price would come from when bitcoin's price is currently a number on a screen telling us how many others believe it has value enough to pay us for it.
Something tells me if the internet were not available, pricing would be a nightmarish prospect.
Without Internet, it's not much. Without exhanges it can be still something...