I have actually thought of this and I agree that it is somewhat of a legitimate concern especially for third world countries where it is very difficult to access the internet with a speed good enough for doing stuff with Bitcoin. There are several unrelated projects which work to get internet access to everyone such as Google's Project Loon. However, I think the Bitcoin community should come up with their own project for Bitcoin specifically.

I think we should make a Bitcoin Radio network where nodes can connect to each other over radio to relay blocks and transactions. If we get a few cubesats then this radio network can be spread across the world and used for connecting people to Bitcoin without the need for internet.