I was a TBC player. A very, very hardcore and high ranked TBC player. I quit a few months before Wrath was released.
I'll likely be coming back for Cataclysm, although I'm not sure what sort of time commitment I'll be able to give. It will also depend on the release dates of DiabloIII and SCII and how much I like those games.
Also, after raiding with a world top 100 guild, I'm not sure how well I'm going to tolerate raiding from the ground up again.
Finally, I'd rather have a root canal than find arena partners at the 2200+ levels. People don't understand that you can't just slap two high ranked players together and have them win every match. Even if you have experience 2200+, you're still going to plateau at 1800, then 1900, then 2000... It takes weeks of strategy and communication to be the best. Too many people expect instant results and don't understand the amount of work required. It's easy to point fingers when you're not winning, but synergy comes at a high price.