Unlike the majority of oldschool games out there, trying to recreate the original World of Warcraft is deceptively tricky, mostly because the game drastically changed from patch to patch. The developers could not simply use the 'latest' patch and call it a day, because by doing so they would invalidate a large swathe of the dungeons and raids, as well as make the majority of PvP rewards completely inconsequential. As such, some sort of compromise was necessary.
In order to solve this problem, as well as give each dungeon and raid its time to shine, the World of Warcraft: Classic devs have now announced their plans for how the content will roll out post-launch. The exact release dates are still unknown, for obvious reasons, but here's the sort of path you can expect World of Warcraft: Classic to follow:
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
While I can understand holding back Dire Maul because of how good its loot table was, especially if you loved doing the "tribute run", I do hope that Blizzard will add it relatively quickly as it is one of my favorite dungeons in the entire game. I've done it more times than I could count, and all because I wanted that fancy epic axe that drops at the end of it! Naturally, I never managed to get the axe, or even see it for that matter, but I still hold Dire Maul in high regard as it is an incredibly fun dungeon to mess around with!
Once Blizzard announces more details I'll make sure to let you know, but until then you can read a little bit more about their content plan over at the official website.