Before the expansion came out, we wondered and wondered what would happen to the old level 60 instances when the Dark Portal opened. And now that it's here, we know: no one's running them. Oh, there's a few quest groups here and there of people working their way up to 58 (the bare minimum to come through to Outland), but there's almost zero reason to run AQ or ZG 20-mans, considering the loot is just so much better, even just in Hellfire Peninsula. And MC, on my server at least, is a barren wasteland-- why take four hours with 40 people just for a few good pieces when you can get much better loot in 15 minutes of questing in Outland?
So what to do? We're sure Blizzard will come up with a way to make these instances relevant again-- in fact, I'd be surprised if, despite what they said earlier, they weren't already working on it now. But just to help them, here's a few suggestions of how to fix the old instances.
-First, and most obvious, is enabling Heroic mode. We already have dungeons in Outland that will be able to be tuned to Heroic mode, which means bosses and mobs are harder, but give much better drops. In the same way, Blizzard is likely going to let us optionally turn up the difficulty in UBRS or Stratholme, offering better loot for a bigger challenge.