The data doesn't take into account revenue coming instead from data that has replaced conventional p2p revenues.

But yes, p2p SMS is going to decline. What isn't, however, is b2c SMS (bulk), as platform such as WhatsApp aren't interoperable and are inaccessible to corporate usage. SMS has the advantage of massive compatibility and the only barrier to the system being the need to have a mobile number of the recipient.

Hurrah for apps!