So what does the future hold for traditional ad agencies and in-house marketing departments using outbound marketing strategies? Halligan predicted outbound's demise as the mainstream marketing methodology in less than a decade.

But Halligan believes many outbound advertising agencies are noticing the changing tide of inbound marketing and are starting to adjust.

"Many of the big ad agencies are starting to realize that, and they're starting to do more content creation, much more on Twitter, much more on Facebook, much more on LinkedIn and much more on the blogosphere.

" As a result of the growing shift, Halligan predicts many large ad agencies will adopt the inbound marketing approach through acquisitions or by building in-house inbound departments. In the end, he believes inbound will win the day.