Blizzard said last month that World of Warcraft Classic will be rolled out in six phases after it goes live this summer, based on the way-back-when update schedule of the original game. Today it expanded on that with details about its content plan for PvP, which will also follow the original WoW release pattern—which is to say that there won't be a "formal PvP system" in WoW Classic when it launches.
You'll still be able to kill your fellow players, though, and entirely without penalty, because no PvP system means no Dishonorable Kills—until the second phase of Classic rolls around, which will introduce the Honor System and PvP Rank Rewards. Those rewards will be the versions from the 1.12 patch, but won't be easy to get: Blizzard warned that "it will require a substantial time investment to rank up through the Honor System."
Phase three of Classic will bring in the Alterac Valley and Warsong Gulch battlegrounds and their associated vendors, although not all of their items will be available right away: The Spell Penetration trinkets from Warsong Gulch weren't added to WoW until the 1.9 patch, for instance, so they probably won't appear in Classic until phase five. Arathi Basin will appear in phase four, and phase six will see the arrival of the world PvP objectives in Silithus and Eastern Plaguelands.
World of Warcraft Classic still doesn't have a release date, but here's the quick-and-dirty rundown of the PvP content release schedule, relative to the planned update phases. (Phase five of the Classic update schedule apparently won't add any new PvP content to the game, which is why it's not listed.)
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.
- Honor System (including Dishonorable Kills)
- PvP Rank Rewards
- Alterac Valley (version 1.12 869)
- Warsong Gulch
- Arathi Basin
- World PvP objectives in Silithus and Eastern Plaguelands
More details will be announced as the release gets closer.