You may have already encountered a massive movement of friends and family migrating into new platforms. I currently see this in Germany regarding Instagram. I have been there for a couple of years now, but lately, I see more and more people creating their account. Sure, Facebook is actively pushing people to go there or giving you the power to invite people to the platform, yet the real movement is coming in 2018.
The most recent case of this is the race for the attention of youngsters between 12 - 25 who just love to broadcast every meal and walk to the dentist instantly to their peers and create a personal reality show. The app of the minute is Snapchat. Even though Mark Zuckerberg tried to buy Snapchat a few years back for a few billion dollars, the app remained autarch and grew quickly. Since Facebook cannot own Snapchat, they will simply try to render them replaceable.