Whenever I want to send something to someone I know, it's an SMS. I can't imagine going into my browser, going to the facebook website, copying and pasting my long password in from the keepass app, looking their name up, opening the message interface....

When I can just click the SMS button, click their picture and go.

People may not cancel their data and get SMS instead but I don't really see SMS going away in any sort of a hurry.