The devs have said that Odin's story would be explained eventually. His fate battle pretty clearly says there's more to it than the players realise when they kill him. It would make perfect sense for there to eventually be a confrontation with him at Urth's Fount as part of the main story...
I doubt anything like this would be exclusive to fan fest though. That would be a LOT of work for something that would only see a few days use. All the primal trials at events were just modified versions of the normal primal trials, nothing completely new like this would be.
