Some people say that there was no pvp in D2 but something more like a pk. To be honest I loved it in there. For me Diablo 3 doesn't has any kind of Duel/ PvP/ Arena or anything else. I seen in D4 gameplay trailer a little fight between two players. Could that be a pvp like in D2 where each players hit the 'hostile' button and then 'go' and start? Or just a 'pk' hunting another player around the huge open world map that we'll have
I wish they will take the game seriously this time and do justice to the brand. I have no expectations myself though. I wish we will have at least a pk feature in the open world. But D3 also promised a lot and cut out feature after feature during beta. They also did blogs and listened to the community but in the end it was a mess.
I wish a lot of things for D4 to get right , but I won't be fooled twice.
D3 was designed from the ground up with no focus on PvP. They were going to have an arena that you could brawl in but it was to be unbalanced and there was no emphasis on esports. I think they eventually added the mode but I don't know anyone that took part in it.
I personally think PKing is stupid, but at least in D2 you can make private games and thus avoid it. I am doubtful they'd introduce a system of that nature without a toggle in an open world system.