What's it all mean? Certainly, the mobility and ubiquity of today's tech devices is changing the way interact with our digital assistants. But the laptop and desktop aren't going away anytime soon.

"So what does 'post-PC' mean, anyway? It doesn't mean that the PC is dead," Epps writes. In fact, Forrester forecasts that U.S. consumer laptop sales will grow at a compound annual growth rate of 8 percent between 2010 and 2015, and desktop sales will decline only slightly.

And while 82 million American consumers will own a tablet in 2015, more than 140 million will own a laptop, Forrester predicts.

"In the post-PC era, the 'PC' is alive and well, but it morphs to support computing experiences that are increasingly ubiquitous, casual, intimate, and physical," says Epps.

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