Math suggests iPhone market share to hit 68% in US by 2017

Apple’s next big opportunity may be in China, but that doesn’t mean the U.S. still isn’t a big market for the iPhone(s aapl). As the country reaches smartphone saturation — the point where nearly everyone has a smartphone — Apple’s iPhone could account for a whopping 68 percent of the U.S. market by 2017, which works out to around 180 million handsets.

The figures come from industry analyst Horace Dediu, one of the best in the business from my perspective. And they’re not based on simple forecasts either. Dediu has a knack for leveraging statistical analysis that’s far more often right than wrong. The numbers for this particular forecast are based on Dediu’s research on smartphone uptake in the U.S.

This graph, for example, measures the historical smartphone penetration in the U.S. and Dediu found that sales of iPhones follow the same velocity as overall smartphone sales.

Asymco US smartphone update compared to smartphone penetration

Compare that to the curve for Android(s goog) share, which rises significantly but appears to have peaked and may be in decline: Essentially now lower than the smartphone penetration rate.

Apple’s iPhone sales ebb and flow on a quarterly basis, yet the trend-line shares the same rate as overall smartphone sales. Add in a little more math and Dediu deduces a nearly 70 percent market share for iPhones in the U.S. once smartphone penetration reaches 90 percent.

Obviously, anything could happen between now and then. The fact that Microsoft’s(s msft) Windows Phone is now on the rise — see the trend starting to reverse on the graph — could play a factor over time. Even a major market disruption in this space, however, would likely take several years to significantly change the smartphone landscape, so I think Dediu has provided yet another successful glimpse into the future.