Don’t waste dev time on PvP. Most people don’t play PvP. If they do anything for PvP it should be another option along side softcore and hardcore that has full open PvP for anyone who plays on that mode throughout the game.
That would be the least dev intensive thing to do and it would let all the peeps who cry about PvP gank to their heart’s content because that is what most PvPers want to do gank people who are just trying to play the game.