Current Challenge Modes to become Feats of Strength
WoW Insider posted recently about Lead Encounter Designer Ion "Watcher" Hazzikostas' tweet regarding Challenge Modes, and now an official Blizzard Blog has surfaced regarding the fate of the current Challenge Mode dungeons.
The current challenge modes will no longer be available come Warlords pre-patch, when the item squish, stat squish and other changes also appear, rendering the scaling invalid.
The achievements awarded by the current challenge modes will become Feats of Strength
The current reward items will remain available for those who qualified prior to the end of the season -- which is when the pre-patch launches
After the pre-patch launches, new players will not be able to earn the Mists challenge mode achievements.
If you want the transmog gear, or the title, or the mount, you'll need to hurry up and get started on Challenge Modes! WoW Insider also has some class-specific guides and further information to aid you in your quest for glory.