I'll be pretty sad to see the Azeroth as we currently know and love to go. So much content and memories to waste. Fortunately, an interview with wired.com gave me hope:

"Wired.com: For people who are nostalgic for the old world before Cataclysm, is there going to be some way to revisit Azeroth as it was before?

Stockton: I think that’s what Caverns of Time is for. We’ll definitely have the ability to do that kind of stuff, but we are also going to do a huge world event leading up to the Cataclysm. Some time after patch 3.3 and after (the Lich King) Arthas is defeated, you’ll definitely see a giant world event that affects the Alliance and the Horde very, very much. It’s going to change everything for them. It’s probably going to last something like a month. Something similar to the zombie invasion before Northrend. It will be something that will roll out slowly over time. But we are planning to do a huge world event, so everyone will know the Cataclysm is coming."

After hearing about the changes, I was hoping the Caverns of Time would come into play to allow access to the old Azeroth.