But that doesn't mean digital experts shouldn't be prepared. "Digital agencies definitely need to be at the very least knowledgeable about understanding offline activities and offline tactics," says Adam Lavelle, chief strategy officer of iCrossing. Specifically, Lavelle says digital agencies should focus on the space where those two tactics intersect to understand how the customer works across a variety of media.

Lavelle suggests that taking on more responsibility in industries with greater online focus would be a good place for digital agencies to start. Specifically, he highlights industries in which 25 to 50 percent of the ad budget is already going to the digital space. Those would be industries such as travel, retail, hospitality and, increasingly, financial services.

Forrester's Brian Haven focuses less on key industries in his report and more on four areas where digital agencies should try to build capacity: measurement and analytics; audience research; social media and cross-channel integration. In essence, each of these four areas points to the same thing -- digital agencies, with their access to clickstream and other user data, need to study and quantify consumer behaviors and desires.

Lavelle agrees and says that's one reason iCrossing acquired Sharp Analytics last year. The acquisition allows iCrossing to make use of Sharp Analytics' marketing dashboard, which analyzes data and compares it with pre-defined campaign goals. Lavelle says iCrossing has already tailored the dashboard to its current campaign for Mazda.

Still, Haven warns that being able to track data and use fancy social media tools isn't enough; agencies need to show dexterity in how they apply their bells and whistles. "Agencies must be well equipped to navigate this new terrain, and they need to possess the discipline and acumen to know if and when each channel or technology is appropriate," he writes.