Blizzard’s original plan was to roll out version 1.12 and then roll through Scourge Invasion over four stages:

MC, Onyxia, Dire Maul, Kazzak, Azuregos (March 2005) Blackwing Lair, BGs and PvP rewards, Zul’ Gurub (July 2005) Ahn’Qiraj, Tier 0. 5 Silithus content, Green Dragons (Jan. 2006) Naxxramas Raid, Scourge Invasion (June 2006)

The company’s design philosophy behind the roll out can be seen in full in the graphic below. 

Over time, these original plans have been modified to include six stages, and a few things are being delayed.

To begin with, Blizzard has decided to wait on releasing Dire Maul to avoid the negative impact it could have on player progression. Blizzard has also decided to separate the releases of Blaickwing Lair and Zul’Gurub while moving the release of the Green Dragons up.

Some of the thinking behind these changes are based on player feedback, but they’ve also been made in an effort to make the Classic servers exude true, original World of Warcraft feel.

To achieve this, the team will be releasing patches in pairs. Each of the six release phases will concentrate on two or three big items, with each item designed to allow players to progress in the same way they would have in the early 2000s.

One of the things the development team noted was that when Maraudon was released it was just after the first player in the game hit Level 60. Dire Maul, on the other hand, contains loot that’s too good to be released in conjunction with Maraudon or other Phase 1 content. 

In fact, a good portion of the shuffling the developers are doing is focused entirely on the game’s loot table. This will also be accompanied by changes to the drop rate and locations of gear. Changes will continue to be made to the game’s loot throughout the six phases.

Here is the new schedule: 

Phase 1 (Classic Launch)

Molten Core Onyxia Maraudon

Phase 2

Dire Maul Azuregos Kazzak

Phase 3

Blackwing Lair Darkmoon Faire Darkmoon deck drops begin

Phase 4

Zul’Gurub Green Dragons

Phase 5

Ahn’Qiraj War Effort begins Ahn’Qiraj raids open when the war effort dictates Dungeon loot reconfiguration: Tier 0. 5 Dungeon gear, Relics, drop rates and location changes

Phase 6

Naxxramas Scourge Invasion

Of course, these plans are also tentative, so players can likely expect more changes in the future.

Interestingly, the developers haven’t made any decisions regarding the PvP portion of the game. The mode’s rewards are still being decided upon.