Juniper Research has projected annual revenues from consumer mobile applications will approach $52 billion by 2016, as consumer smart phone adoption accelerates in tandem with the emergence of a mass tablet market.

The forecast raises some pertinent questions.

Just what will that new revenue stream indicate about the emerging role of tablets in the device universe, and what, in turn, tablet apps might mean for the devices we know as "personal computers"?

Much will hinge on how that new revenue is created. Some will consist of content purchases. Others will be provided by in-app purchases of digital and physical goods. Some of the revenue will come from advertising and promotion. Other revenue will come from software purchases like app sales.

Those shifts will affect the way PCs are designed and used, more than the others. Kip Cassino, Borrell and Associates EVP argues that by 2016, most computers available to consumers are going to look and act just like today’s iPhones and iPads. That means they will be able to communicate like cell phones, all have built-in GPS and feature cameras and touch-screen interfaces.

Most importantly, Cassino argues, they will depend on apps instead of expensive, bundled software.  In fact, what we now call computers will have largely faded from the scene, except for some business and gaming applications. Personal computers will be replaced by mobile devices of one sort or another.

You don't have to agree with the time frame, according to Cassino, to agree with the direction of the user experience.

You might argue the biggest possibility of change will occur if revenue sources shift to content sales or in-app advertising and commerce, as those sources will tend to correlate with use of a computing device as a content consumption platform.

App sales alone might suggest either a change in software distribution or a shift in end user app usage. The latter, much more than the former, would be big.

In the near term, we are virtually certain to see experiments that combine the “mouse and keyboard” interface with a “touch screen” interface, much as early steamships had both steam engines and traditional sales. That didn’t last, and there is reason to believe the “hybrid” interface won’t last either.

“Touch” is arguably the preferred interface for transactions and content navigation. Mouse and keyboard still make more sense for “work” and content creation (writing, editing a movie, working with a spreadsheet, etc). Ultimately, touch may become the preferred interface for most consumer appliances, none of which are used for “content creation” applications more complicated than taking a picture, sending an email, text message or content sharing.

PCs will still be valuable for "work." But most consumer applications center on content consumption, with content creation activities that can be handled with "touch" operations. People will try hybrids. But in the end they will choose appliances that are optimized for the "main" use case.