Depends on how you define the product category. What teenagers used Facebook for 10 years ago, they use Snapchat for today. But what adults used Facebook for 10 years ago, adults still use Facebook for today.
> But what adults used Facebook for 10 years ago, adults still use Facebook for today.
I am a twenty-something without a Facebook account (used to have one, though). IMO, there isn't much I would want to do with Facebook that I can't do with email or texting.
I was answering the parent's question: if by "alternative to Facebook" you mean that you want the thing that made teenagers use Facebook in 2007, then the answer is that Snapchat is a viable Facebook... somehow. (I'm not too clear on how exactly myself, but it seems to work for them.)
