One week ago Microsoft made their announcement about Windows Phone 7, during which we learned who will be selling what devices and when they will be available. Since last week there has been a fair amount of commentary about whether Windows Phone 7 poses a threat to Google or Apple, along with commentary about the probabilities for success. As basically a new entry into the market, Windows Phone 7 will be measured against whether it takes market share away from Google and Apple. Of course, there is another way that Microsoft can succeed, and that is by attracting new smartphone owners and thereby capturing a greater share of the smartphone market growth than Google or Apple.

According to CNN, using data from Forrester Research, only 1 in 5 American’s own a smartphone. In other words 4 out of 5 Americans either don’t own a cell phone, or own a “regular” cell phone or a “messaging” or “feature” phone. If three of those four people decide to by a Windows Phone, Microsoft will grow it’s share of the market and prevent Google and Apple from gaining new users. Put in yet another way, Microsoft isn’t concerned about converting current iPhone and Android users to Windows Phone, they are concerned about converting Samsung Gravity and LG Cosmos users to Windows Phone.

If a cell phone user decides they want to step up to a smartphone, Microsoft needs to be in the running for consideration between iPhone and Android. Certainly, Apple and Google are formidable competitors, but I think Microsoft has a bigger obstacle to over come. Recall the failure that Microsoft recently experienced with the Kin. One can debate about whether the Kin had too many technical gaps to be successful, but few would debate that perhaps the major reason why the Kin did not sell is because it was too expensive. The target market for the Kin was a subset of the Windows Phone 7 market I describe above, a market which today might pay as little as $30 a month for a voice only plan, or perhaps $40 per month for a voice and text messaging plan. Are those customers able and willing to pay an additional $20 per month that a will be required to own a Windows Phone?

Microsoft and its supporters rightfully note that the overall cellphone market is huge in comparison to the current smartphone market, as Forrester’s data suggests. However, if current cell phone owners have not already switched to an iPhone or Android phone, why not? For the people remaining in the market, features and capabilities are not the only issue they consider.

Current cell phone owners are likely to be much more price conscious than current smartphone users. In my opinion, ars technical has identified the main obstacle to Windows Phone 7′s success, the high price of cell phone plans in the United States. I understand that the global market, which has lower plan prices, is larger than the U.S., but because the U.S. leads the technology industry mindshare, I think Microsoft’s success will be measured by how well it does in the United States.

In the end Kin failed because it was too dependant on Verizon for its success. When Verizon was unwilling to create data plans tailored for the Kin, such as they did for the iPad last week, and put the Kin on their regular smartphone plan, Verizon doomed the Kin to failure. If my theory holds, even though Windows Phone is technically superior to Kin, it may suffer from the same weakness of being too dependant on others. At least this time, Microsoft won’t have to rely on one carrier and that increases the probability that it could fair better than Kin. In the end, though, Microsoft is very much at the mercy of the likes of AT&T and T-Mobile and that cannot be comfortable.