A PriceWaterhouseCoopers forecast issued today says advertising levels will only in 2015 recover to their 2007 levels. By that time, China will have surpassed Japan as the world's second-largest media market and more than 30% of advertising will be in the digital sphere.

The report asserts the recession accelerated the transformation of the advertising business to digital. It says the United States and Canada were hit hardest by this change and will be slowest to rebound. Worldwide, advertising declined 11.8% last year.

It predicts 3.9% compound growth in North American advertising but stronger growth in Europe (4.6%), in Asia (6.4%) and Latin America (8.8%).

One other observation in the report: Consumers are shifting loyalty away from Internet and mobile phone providers and to the smartphone and tablet devices themselves.