29, my parents and their friends 60, 70+ all use whatsapp instead of SMS. Whatsapp, Messenger, Google Talk, even Jabber… With modern smartphones it's all the same, the only difference is who's on what which is why I hated when everyone moved away from XMPP.

19, it's like 30/70 SMS/Facebook in my experience. (Then there's Snapchat, but that is more of an overlap than a replacement.) I think part of it is that Messenger handles groups well and everyone is on it without needing a number.

Frankly I hardly use Facebook-the-social-network much, but I use Messenger all the time.