Couple months ago, GC mentioned that there was an unannounced feature coming in 5.3 that he was excited about. There were some hints.. the first is that a lot of people would go ´meh´ when it was finally announced. The second hint was that it would add a lot of content for some players.
Did I miss where it was announced, or cancelled? The general consensus is that it was going to be the ability to queue to do lower level dungeons and get scaled down..