Is there is a correlation between the increase in Selfies versus the growing trend of teens leaving Facebook?
They key in understanding the future of each of the services is in their mission statements:
"Give people the power to share and make the world more open and connected"
The mission was shared with Zuckerberg around IPO time, and also explained in detail in his letter to investors. The mission is two part - 1) Give people the power to share 2) Make the world more open and connected. Facebook does a damn good job at it. For Facebook, relationships are open, one-many and long-term.
Compare Facebook's mission statement with Snapchat's (unofficial) mission:
"Capturing and sharing moments with your friends in real time"
For Snapchat, relationships are secretive, transactional, one-one and short-lived. In the short term, Snapchat may have more brand recognition and utility with teenagers than Facebook.
Facebook cannot be everything to every person. They are thinking in the right direction with segmenting their users and creating standalone apps/experiences for each.
1) Instagram - For the photo takers / producers
2) Messenger - For the texters
3) Paper - For content consumers
4) Facebook - For content producers
5) New Product/Feature - For Live Broadcast.
Video is ultimately going to trump text as a medium of communication and expression. I'd bet that Facebook will launch a competing video broadcast product to stay on top of this trend.