From what I know, the most populated PVP map was 24v24v24. And since they changed the PVP roulette, at least in my experience, queues take longer. I hardly imagine they add "Open World PVP" maps since duel and small scale PVP doesn't look that popular.

In one of his last interview, Y-P use the word "casual" and "Small Scale", he also talk about PVP as a "niche" content, it's pretty unlikely "Open World PVP" to occure.