Can legacy agencies compete? They're too big, well-funded and full of talent to count out. Peter Kim at Forrester recommends no less than a complete re-organization of how agencies work with clients and how they go to market.

"Agencies organize around their own silos, promoting either discipline-centricity (e.g., account management, creative, media and research) or media-centricity (e.g., television, print, out-of-home and digital)," Kim wrote. "Marketers should select agencies that employ an approach to campaign planning that favors no particular media, but takes a customer-centric approach. Doing this well means using the customer as a campaign's organizing principle. Agencies that do this well anticipate interactions through the entire purchase funnel and build relationships, starting with awareness and closing the loop with loyalty."