This Engadget post references some less-than-scientific reports that claim many (as much as 50%) of the Storm devices are being returned. We can’t confirm this figure, and I doubt RIM will do so.
However, these previous Storm users are most likely migrating to other smartphones – Apple iPhone, BlackBerry Bold, Windows Mobile, Palm OS, or the new Android-based G1.
Rest assured your sync needs are covered with CompanionLink, which will sync with any and all of these platforms.