Which is presumably what the OP was talking about. MySpace was hyped and valued beyond belief, and then came crashing down. The same could well happen to Snapchat.
Having said all that, I'm judging it from anecdotal evidence available to me. None of my friends use snapchat (all late twenties and early thirties) but they do use twitter, fb, vine (on occasion), whatsapp etc. The only people I know that have snapchat on their phone and use it regularly are all < 23 yrs old. Of course, could simply be my friends and I are totally out of touch!
Edit: interestingly, just realised none of my friends (female or male) use pinterest either (which, from what I've read, has a wider demographic). So maybe we're just a bunch of luddite weirdos...
It would be interesting to know what's the percentage of Snapchat users still use it daily after high schools. That would make or break the whole company.