As long as it includes options to auto-deny any and all PvP requests and chat filters to block PvP related /tells. Most of the 1v1 PVPer's are a plague on the MMO community at large, even better if they do add it they could make it available only with someone on your friend list to keep it friendly. The last thing I want to see is e-peen battles in my FFXIV.
That being said I'm actually looking forward to some team battles as it will require some tactics to cover each others weaknesses.