Holy cow. That's a big thought, at least for me. What would I do? I don't think I'd start over. I would miss WoW, but I've been wrapped up in this game since I Beta'd for it. True, the game's community is so much different than it was once upon a sunny time when it first was launching, but I still have found ways to love it. Losing that would represent things I couldn't ever recapture. Incredibly lucky finds that I'd never be able to repeat (such as when I won the Chromatic Carapace in UBRS against 3 other rollers with my roll of 34), progress made on things that were an f-ing beating but I got through it so I could be done with it (Cooking comes to mind).
I am pretty sure that I'd take it like Maube -- it would be the end. Wash hands, dry, walk away to other things.
It's such an excellent question, though, because I would miss it and dream about returning. It would be a chance to have an "alternate universe" experience and do things differently. I am afraid my designs are not for public consumption, though, as they speak of present situations, past regrets, and of plans/ideas that I don't want to be misunderstood in my current situation -- assuming of course there's a current situation to return to.
Losing our characters... I highly doubt that's what we're looking at though. It certainly is possible in the world of data and code, but can you imagine what it would do to Blizzard's game and their reputation? Talk about a storm of poop, with lots and lots of "rain".