"Since we broke down the six phases of content that we’ll be rolling out for Classic, we’ve heard the increase in requests for PvP details so we wanted to get you up to speed on our plans there.
As was the case when World of Warcraft originally launched in 2004, there won’t be a formal PvP system in WoW Classic at the outset. You’ll still be able to PvP, of course, and there will be no Dishonorable Kills, so you’ll be free to repeatedly hunt down every player and NPC in, say, Stranglethorn Vale to your stealthy heart’s content.
That’ll change once phase 2 rolls around and we add the Honor System, which will introduce Honorable Kills, Dishonorable Kills, and PvP Rank Rewards. The items you earn from the PvP Rank Rewards will be the versions from patch 1.12. Keep in mind though, just as it did originally, it will require a substantial time investment to rank up through the Honor System. For those interested in the Rank Rewards, earning epic gear will require consistent dedication over a long period of time as a top contributor on your realm. We don’t expect to see many people running around with these items early on, but we’re certain Hillsbrad Foothills will still see its fair share of action!
In the third phase, we’ll introduce the first Battlegrounds: Alterac Valley (version 1.12 ) and Warsong Gulch, alongside with their associated vendors. One thing to note is that there were a couple of updates to these vendors over the course of the original patch releases, so some items won’t be available right away. For example, the Spell Penetration trinkets available from the Warsong Gulch vendor weren’t introduced until Patch 1.9, so we’re currently thinking that we’ll add these in phase 5.
The Arathi Basin Battleground will follow in phase 4, along with its specific vendor. It’ll be interesting to see how many people stay behind to guard the flag. 
Finally, in phase 6, we’ll have the world PvP objectives in Silithus and Eastern Plaguelands, which will come out at the same time as Naxxramas.
Here’s what the PvP content looks like mapped to the phases we recently posted about:
Phase 1 (WoW Classic Launch)
- You can PvP one another in the world, but there is no tracking, and no formal rewards for doing so.
Phase 2
- Honor System (including Dishonorable Kills)
- PvP Rank Rewards
Phase 3
- Alterac Valley (version 1.12 )
- Warsong Gulch
Phase 4
- Arathi Basin
Phase 6
- World PvP objectives in Silithus and Eastern Plaguelands
As we mentioned before, we haven’t yet determined exactly when each of the content phases will occur but we’ll keep you updated as they draw closer.
We’re here reading what you have to say, so we wanted to thank all of you for your feedback and discussions about Classic. Keep it going!"
Old Blue post.