Phasing. I think it would be great if next expansion early on we went to the Dalaran and did some quest chain that was resolved late in leveling that expansion that ended with the destruction of that city and the true central hub was revealed at that point where all the survivors gathered.

You could make it work with an instance, and make it make sense, and still give it loot. That would keep players doing this.

Allow me to demonstrate:

Massive war-dungeon, you lead a small brigade of troops dedicated to wiping out a valuable strategic point for the Lich King. Failure to take this point will lead to the slaughter of hundreds of troops in a valley below. So far, so good.

You charge in as usual, and do some excellent work killing various groups and bosses. One of the latter ones drops some loot and a 'tightly locked chest' that can only be opened in the "______ Rise" ending area of the dungeon (this contains the major loot). Then, you go into the final battle, NPC soldiers all around you, against one of the Lich King's trusted lieutenants... and once you reach a certain point, he moves to wipe the floor with you. NPC soldiers die in droves and some clever attack does slow damage to everyone just for being there. NPC soldiers yell, "Retreat!" and it should become clear that's the only real choice. You flee with them, entering the TRUE last boss fight -- A gauntlet of small mobs and monsters that need to be either run past or killed fast enough that the party doesn't wipe to the slow, constant damage. (HoTs here could be vital to survival.) As you break out of the dungeon, onto the "______ Rise". And you get to see the soldiers march into the valley... and be slaughtered horribly. You know you failed, and the price of your failure.

The loot in the chest is a cold comfort.

Another idea, what if Arthas himself was the one who swoops in to send the attackers running? Even better, what if we got a chance to fight him for a bit before we went for the retreat? That'd be fun.

Or maybe even a 'heroic defeat'. What i mean is, those brave adventurers, stay on fighting an impossible battle, the longer we stay alive and killing things (guarding the retreat of those fleeing soldiers/refugee/npcs) the better loot you eventually recieve. The mobs get harder, until maybe arthas or one of his top sidekicks comes to kick our tired and oom asses.

Not only is the defeat a good idea, but something that will refresh wow a bit imo. Would be quite nice if they released it WITHOUT it being on the PTR so no-one knows the thing before it goes live too. Personally id LIKE a few fights that noone had strats for (maybe changing tactics during fight so ppl have to be on their toes). BTW yes i know i dont have to read strats, but show me a guild that lets you do exactly that, esp when your a ranking officer. Also its pretty hard not to get told em, and a little daft to let down your guildies so you get a 'surprise'.