The truth is that BW is focusing on story mode, as they said on the stream. if they put any pvp content, and i emphasis "IF", it would be another arena.
i think they will not put any other open pvp area, when the realty is, that no one enters it.
be sincere, how many times have you enter the outlaw's den, for anything, other than the purchase of the quest thingies?
we just have to keep farming ppl on gree event, RG event, and any other who forgot to turn his flagged pvp option off.