As I read the interview on Monday in MediaPost's Online Media Daily with Digitas’ Chia Chen, who leads the company’s mobile practice in North America, I found myself agreeing with just about everything he said.Whether talking about the position of the mobile sector now versus a couple of years ago, brand activity in the space, shifts in budget allocation or the need for standards, it all made sense.But his opening words stopped me short. Chen declared: “We’re in the post-PC era of digital, and mobile is the primary way people are connecting to digital.” That’s a pretty big statement to make -- even if made during the frenzy of this year’s Mobile World Congress in Barcelona.It’s not that I don’t fully believe that mobile media is massively important now and that this importance won’t grow. I’m just not convinced that we’re at the “post-PC” stage yet -- or that we ever truly will be.After all, the history of media has shown us time and again that few media categories are completely eclipsed by the advent of another. The hierarchy tends to shift to make room for newcomers, but as societies, we seem remarkably adept at assimilating new media channels into our lives. The only notable exceptions are the Pony Express and the telegraph, both made redundant by the locomotive.But what does the data say? Are we there yet? Have we become “post-PC”?A quick look at reach numbers from USA TouchPoints for use of computers and mobile phones for adults 18-64 throughout the week suggests not. But the total user figures also suggest it’s a close-run thing -- with total weekly reach for computer amounting to 87% and for mobile 88%.But that isn’t the whole story. Within those numbers is mobile talk and use of computer software, neither can be considered media opportunities for brands nor agencies.If we strip talk and software out and just look at Internet use via computer and use of the Web and apps via mobile, we see total weekly reach of 80% and 48%, respectively. On these terms at least, one can categorically say we aren’t yet post-PC.Perhaps the real point is not the numbers now, but what the numbers will say in the future. Mobile is clearly growing and no-one believes it will stop any time soon. But the problem with phrases like “post-PC” is that no matter how memorable they are, they engender a perspective that wrongly states the medium it refers is redundant. And that may not be the intent of the speaker, but often the interpretation (consciously or otherwise) of those hearing and repeating it.The real point for mobile -- as for other media in the past -- is less about surpassing other mediums and more about find a powerfully complementary place in consumers’ media day. That way, brands can develop a clear understanding of where and how to take advantage of the medium’s strengths to leverage not only mobile, but how it can be used to leverage other media, including online via PC.So what is the answer to the title “Are We There Yet?” A resounding “yes” -- if asking about our arrival in the mobile era. But an equally strident “no” if we’re talking about the passing of the PC age.After all, I’m writing this on a laptop with voice capability outside of an office. Isn’t that a mobile medium?