I'm not sure why so many are predicting WPs death - it's actually doing pretty well outside the US. Here in the UK it's now just under 10%. Pundits are far too US orientated.
These things don't happen instantly now that so many devices are alike.
By comparison, when we adopted the first iPhone, it was a dramatic departure from previous cell phones and we had to have it immediately. Since then, we've just waited for our contract terms to expire.
Though I would interrupt my contract immediately if someone would deliver on personal application omnipresence, making a cell phone that is just a small touch-enabled view on my network and my applications.
Trouble is, the US is a large and profitable smartphone market. And it's locked up by the on-contract subsidy model.
There is a strong relationship between iPhone market share and subsidy amount. Countries with no subsidies have very few iPhones. Countries with some subsidies have some iPhones. The United States has high subsidies and thus a lot of iPhones.
http://www.tech-thoughts.net/2012/05/proof-of-iphones-depend...
To some extent, Apple has a protected home market. Regardless of how its market share declines overseas, Apple will still rake in enormous profits through the cellphone subsidy in the US.
This is something that Nokia/Windows Phone doesn't have, with its puny 3.5% US market share. They're doing OK in the markets where people look at the price of the phone, and not doing well in the one market where people are happy to have their pockets picked.
That's not a recipe for making large profits in the phone business. And that's why the US market matters. Profits are disproportionately large compared to revenues.
Microsoft now owns all of Nokia's handset business, which is still 90%+ non-WP. As the S30, S40, and Asha base under WP evaporates, WP will have nothing to piggyback on in these markets.