What if Derek and Addison never broke up? What if Ellis Grey never suffered from Alzheimer's? What if at least one victim from the Seattle Grace shooting survived?

Grey's Anatomy will ask all these questions and more in a special February Sweeps episode that will take place in an alternate reality, according to Michael Ausiello, one that brings back Kate Walsh and other series alums.

Remember when...

Everyone will be "affected,” by this hypothetical dimension says an insider, though no word has been given about how or why these what-if scenarios come about.

What do you think, fans? Is this a cool, fun idea? Or - like many felt about the ill-fated musical episode - is it a desperate ratings stunt for a show whose numbers are slipping? Sound off now!