I've been thinking about this for a localstorage based app that I'm tinkering around with. You can do webrtc without a STUN server, but it requires exchanging a chunk of ugly metadata with another person.
I've been wondering whether IPFS might be a good answer to that - there is this, which supposedly works in the browser. https://github.com/ipfs/js-ipfs
Dump webrtc metadata onto ipfs, give the user the hash back as a "document key" (and maybe a password that was used to encrypt the webrtc metadata) to share with other people; they paste in the key, enter password, and tada, you have a multi user application backed by localstorage.
Of course this wouldn't survive a user changing IP (and perhaps other network attributes) but that might be an OK feature.
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