It depends on how segmented the internet gets. As long as there's enough traffic of some sort between segments, it's at least possible that stuff can be hidden well enough to get through. If necessary, using covert channels.

But if there's no traffic allowed between segments, it becomes much harder. Then you're left with workarounds like this: https://www.wired.com/2016/04/ingenious-way-iranians-using-s...