In theory, there is no reason it can't scale indefinitely using something similar to IP. It's already a self-building network. The hard part is how you incentivise transit nodes. Currently that's what ISPs and backbones provide. They are incentivised to interconnect because that's their core business model. So a truly decentralized Internet requires a decentralized incentive system.

This would enable circumvention, but it's also pretty easy to triangulate radio signals, so it's fairly easy for a belligerent organization to track that someone is sending something.