One thing we are seeing is the pervasive growth of inbound marketing, which interestingly blends many of the same tactical and strategic elements of public relations with content marketing. In PR we don't buy ads for clients to get them covered in the news media, we instead identify what is most unique, credible and newsworthy about out clients and tell that story to the news media, industry influencers and potential customers in hopes of getting them to say great things about our clients, (see earned media). We use tools like press releases, media relations, speeches, social media, podcasts, blogs and more to achieve those ends.
My agency helps clients achieve a high status level of credibility through earned media and other efforts so that prospective customers seek them or their brand out. The ultimate success is when our clients become known to new customers (for want of a better word), then delight these customers so much that customers become brand ambassadors.
That, in essence, is what inbound marketing does. Not too far off from PR.