I like the idea of using raspberry pis + baloons + cellphones to create an alternative/parallel network. But you'd always face issues when trying to go international. The scenario that comes to my mind is someone (or a group) very rich and somewhat influential building a small scale worldwide private network completely segregated from the current Internet. Any attempt to install backdoors, "Y" devices etc would be detected and mitigated. Infiltrated "agents" would be tracked by their behavior and exposed to public attention.

But then comes the real reason for building such new network: communications, content sharing and services. The current availability of those 3 elements should be present. Are organizations willing to maintain two instances of their existing services, one in the current internet, another in the new one? Quite a challenge.

Maybe having the new network solely for secure P2P communication via voice, chat and email would be a good start.