I don't think Square Enix would be ballsy enough to do this as it is. The best we've got for the time being is the Wolves Den.

Though I would like to see an expansion to the Wolves Den. Would be fun to have a "Gurubashi Arena" style area in the wolves den you can just jump into and gank people in. Or get ganked in. Maybe throw a tomestone prize in the middle of it every few hours to spice things up. Oh, and if anyone replies to me saying "But its toxic! People will be big meanies! They'll gang up on people!" What ever stopped you from forming up a group yourself to go smash some arrogant clowns? Big ego's will get checked eventually, and when they do it's all the more satisfying.