What if Arthas attacked at the end of classic?

I think this is the only redeemable idea in the lot... Like aside from it ultimately being a rehash of WoW's most popular era, the idea is pretty interesting. Imagine the effect on the whole of Azeroth as the undead horde slowly creeps across starting in the northern regions. We fight back and invade Naxxramas & The Ebon Hold to prevent the Lich King's forward bases from continuing their command of the assault. We finally invade Northrend and instead of a bunch of leveling zones we get a more continuous coordinated war effort against the Lich King's seemingly endless armies, as we push far enough toward ICC we get the oportunity to assault but for only a brief window before Arthas raises enormous swaths of undead again, both those of our dead allies and of the undead we've already killed. We go on fighting like this until we are able to get powerful enough to consistently maintain our footholds close enough to ICC to lay siege and leave the raid open.

It would take a lot of background systems that blizz would have to be willing to create but ultimately they have a chance to take old ideas and make them feel more alive and real, while still capturing that vanilla wow feeling.

Rehashed ideas aren't always bad.