I'm enjoying the game of checkers Nokia is playing with US carriers/service providers.
I have always believed that the "game changer" in North American markets will be the definition of the "customer".
In North America the customer has not been the end user but the carriers themselves. Nokia, I believe wants that to change and a Linux device in particular a Maemo device will change that... slowly. Very slowly relative to market share.

I also believe what qole posted but with regard to connectivity, I believe all future Maemo devices will have cell connectivity, but not all will necessarily emphasize a phone.

The next move in North America will be the 3G Notebook and devices like it. Will carriers offer data only plans? If they do, Nokia will have moved a bit closer to what I think is its goal here.

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What led the initial growth of cell service in the US was Goverment and Enterprise accounts. Many cell phone users are not the real customer either.

Reggie recently pointed to notes from a talk given @ Mobius 2009 that indicated that more developed countries are OK with having multiple devices.

I think the success of Kindle may indicate this as well.

What ever may come, I'm thinkin' these last two points will have some bearing.