I dunno, for me college always just seemed like an extension of high school. There's not a lot that's all that different - the drinking's legal and nobody has to worry about statutory rape laws, but that's it. Thematically it's basically the same thing. A story set in adult life does carry some more restrictions, but it has an actual different feel to it.
Anyway, I wouldn't start a new story with the YAWYW characters. Either you'd keep the stone, in which case the only thing that changes is the setting and what's the point, or you have the same characters minus the plot device, which would be confusing and people would wind up forgetting and putting it in anyway. You'd do better to create a new core cast.
