Every Android app can do IPC with Android apps in the same profile. So an app without Network Access could cooperate with an app with Network Access to communicate with the outside world. Of course, most notably, a lot of apps communicate with Play Services and people generally leave on network access for Play Services to avoid breaking to much stuff.
There has been talk of developing 'IPC scopes', similar to how there are contact scopes.
IPC scopes would be a great solution!