Firefox is in the early phase of implementing support for non-HTTP protocols, starting with Tor. My understanding (from reading some Mozilla comments here maybe?) is that their goal is to make this pluggable so that eventually Firefox can support all kinds of non-standard transports, including p2p ones like dat://

We’re not there yet, but Mozilla is making a very positive step in that direction, and hopefully other browser vendors will follow. If I were creating a new protocol, I would be doing it now, to “skate where the puck is going” as they say.