Stratholme, the Scholomance, Blackrock Spire and Dire Maul are all lost. Just before Burning Crusade was released some friends came out of retirement and sharpened their blades again, to get ready for the opening of the dark portal to the Outlands, and we entered some of the level 60 dungeons. I had visited them many times, having done so before becoming raiding Molten Core and beyond, but they had not been in them much at all. It was great to run them, much better with friends, and they are a lot of fun.
And then Burning Crusade hit, the dark portal opened. I opined that the level 60 dungeons would not be run, because the quality of loot in Outlands surpassed just about anything found in the dungeons (and I still don't accept any reasons I've been given why the loot was made relatively so powerful in the Outlands). I was told that that wouldn't be the case, and that people would still want to explore the dungeons as the content is still interesting.
But, sadly, the instance runs stopped. Sure, the instances are fun and interesting, and quite well designed. The problem was overtly highlighted when we completed a quest in Scholomance and got a previously-amazing blue quest reward weapon that turned out not to be as good as a green drop one of us got the day before in Outlands. We battled for a couple of hours, defeated the end boss in a challenging 4-man battle, and got no tangible reward from it apart from the sense of achievement. It was fun to do, it was a good achievement, it was nice to see the dungeon, but there was certainly no point in doing it again. What with all the new zones and new instances in the Outlands, there was far more to explore without having to spend a few hours in a level 60 dungeon where there is realistically zero chance of getting even an incremental reward of loot.
Maybe I just think it's a shame because I have fond memories of all the class raids and five-mans I ran through the dungeons, finding their secrets, getting to know them inside and out. I certainly don't care too much that I'm no longer running Uldaman or Scarlet Monastery, because there are greater challenges to face. Even so, the level 60 dungeons are not even going to be used as a stepping stone to the next levels any more, because of the easy progression through from Azeroth to the Outlands and the significant increase in loot that can be gained in the Outlands over Azeroth. When you get past the Sunken Temple and have gone in to Blackrock Depths a couple of times, it's far more rewarding, and a better investment of time, to head to the Outlands and get ready for Hellfire Citadel than to head off to Stratholme. There are some wonderful adventures to be discovered but are being ignored, and that is a terrible shame.