Patch 6.2 for World of Warcraft will bring a new feature called Timewalking, a feature that makes The Burning Crusade and Wrath of the Lich King dungeons worth playing even if you're level 100.
Any characters who are level 71 or above can Timewalk through The Burning Crusade dungeons. Anyone level 81 and up can revisit Wrath of the Lich King dungeons. When you Timewalk in these dungeons, your character's gear and stats are scaled down to the appropriate level. However, you'll still have all your skills and talents from your normal level.
You won't just end up with bags filled with obsolete loot, though. Instead, Blizzard will be updating "most every piece of loot" in these dungeons. This "Time Twisted" gear will be appropriate to your character's true level. In other words, if you're a level 100 character playing Utgard Pinnacle, the Red Sword of Courage will be item level 640. Presumably they won't keep scale up as you level like Heirlooms so you'll have a reason to revisit the Timewalked Dungeons at a higher level.
Timewalked Dungeons will be available during special weekend events. It sounds like only one old-school dungeon will be available during each of these weekends. In other words, it could take a few months to see all of them. Like Garrison activities, these weekend events are another way Blizzard hopes to get players logging into World of Warcraft at a steady rate. Because of the game's monthly subscriptions, they don't want players to just blow through all of the game's content quickly and then stop playing.
Players will be able to try out Timewalking, along with the rest of Patch 6.2, on the Public Test Realm. Blizzard says on their website they will be testing the Timewalked versions of the following dungeons in the weeks ahead:
This patch will also allow level 100 players to travel to the Tanaan Jungle zone. They'll find a new raid, Hellfire Citadel, along with a fresh set of dailies. These daily quests will give them resources for a new Shipyard building for their Garrison. You can check out much of this new content by downloading the PTR client now.