I am confident that Scirra will release a tutorial or software for a "host your own" Signalling server as the Multiplayer object has the connect function allowing you to enter a url for a signalling server.
So they wouldn't just let you place a custom url unless they have plans for it, same goes for whatever an ICE server is.
Still, it would be nice to just hear back from the scirra team with what the future development plans are for the multiplayer options.
End of the day, i dont really want to have to rely on an external internet server to play a multi player game when ill most likely be playing it on LAN with my friends in the same room.