Now, during Friday's fanfest Yoshida was asked about possible open world PvP. As far as I can see no one's made a specific thread yet about this, as he did wish for player feedback on the topic.
It was also mentioned that, due to the knowledge that some people would not want to PvP in the open world, they would create specific realms for players to go to to PvP.

Question is, do you think this game needs open world PvP? Do you think it will bring in more players? If it was implemented would you prefer it was for all servers (but optional like in WoWs PvE realms), with specifically PvP enabled servers added, or only for specific realms with our realms kept the same?

I personally wouldn't want forced PvP on my realm, Odin, as I'm a "care bear" who only PvPs when I want something. Optional PvP would be fine with me. That, and it would possibly make people actually use the open world that little bit more.

Other than that I think maybe it would be cool to have a map created that is PvP specific, like a few MMOS have already done, where you go to PvP for rewards, etc. However, there is the issue that this map might not be used as much on a PvE realm since most of us play FFXIV because it centres around PvE in the first place.