In my opinion, they are starting with the wrong question. I think the die has already been cast on the importance of social media and whether or not it should be an integral part of SEO. (It should.)
The real question is, “Can SEO thrive without social media?”
To that, I firmly believe the answer is “No”. Not today, and not for as long as social media continues to play a role in shaping society. Until the great EMP hits, I don’t see social media losing its grip on how we live our lives. Which means, search engines will look for ways to incorporate certain social signals into their ranking algorithms. And rightly so. Social media, essentially, is the real-time pulse of what we like, dislike, love, and loath. It only makes sense that search engines want to measure this in order to make rankings more relevant for both the masses and each person individually.
Read more at http://www.searchenginejournal.com/social-media-changed-seo-business-cant-thrive-without/119658/