At the moment WP7 is an obscure product, if Nokia successfully push the OS then Microsoft will gain hugely (being the owner of the platform), whereas Nokia will suddenly face competition from manufacturers with much smaller margins.
Agreed, that forces them to keep churning out designs products that the public perceive as premium and the competitors can't easily replicate.
They might then look at leveraging the right to modify the OS that no other OEM got, apart from a big bag of much needed cash from MS to survive this year without spiraling down in the face of marketshare losses, so I guess that evens it out a little.
