I remember seeing Mark at an F8 conference, an early-ish one with the SNL impersonator. He joked that Facebook took MySpace out back and shot it in the head. Seems Snap is next.
http://www.hollywoodreporter.com/news/andy-samberg-parodies-...
Hard to see that anything fb does can come close to 10x better than Snapchat. They can (already have?) achieve parity easily by copying, but that will only gain them a very gradual shift at best — nothing like the radical shift from myspace to facebook.
Regarding Myspace, I'd even suggest that they shot themselves and Facebook was well positioned and well designed to take the credit. To put it another way, I think myspace would have eventually imploded even if facebook hadn't existed. But that's wild supposition that I wouldn't claim to be able to back up with any evidence. I just know that I was 100% done with myspace long before I found fb.