Yesterday, I suggested a few ways that Blizzard could make the "old" instances (Scholo, Strat, UBRS, MC, and on up) relevant to players again, and from that conversation came a few good points that I figured were worth mentioning. The problem isn't that the old instances aren't fun (they are still fun, and I've heard that some guilds are still planning to run them, even if they don't need the equipment from them). But the problem is that if you want your character to have the best gear in the least time, the "old" instances are a waste of time. At 58 you should be in Outland, doing 15 minute quests for better-than-tier 1 items.
Tobold agrees with me-- it's very likely that players who reach 60 after expansion release will never run Molten Core or the other instances the way they've been run in the past. Either Blizzard will change the levels on them, or players will go back to them for fun with a mix of 60s and 70s. Both of those are very different experiences than the one of learning as a guild, week after week, how to run MC. I don't mean to be depressing (the idea is a little bit softened by the fact that the same thing will be happening at 70 now, only in smaller, easier to manage groups), but it's true. Goodbye, MC.
There is one more idea, however, that came out of yesterday's thread that I thought was pretty good. Reader Skew came up with an idea that seems so ingenious, I wish I'd thought of it. What if Blizzard turned all the pre-Outland instance gear into BOE? That would create a demand for someone to constantly run them, not just for the gear, but for the enchanting mats and so on. Yes, it means that with enough money, you could come by a set of tier 2 without ever going to BWL, but also remember that tier 2 isn't that valuable anymore-- the stuff in Outland is what we really want. I doubt Blizzard will go for such a "giving" solution, but you gotta admit: it solves a lot of problems with a pretty simple change to the code.