Yes I think so, hidden onion services are only accessible via tor.

And possibly we would have to run some tor-relays to bear with the higher traffic.

Ecash could help incentivize such a network without relying on altruism alone.

There are other protocols like i2p and freenet (and possibly mesh networks and such) as a substitute or fallback but I think at that point no one would be able to predict how that situation would really play out.