It's Nokia that gave up on the US networks after they wouldn't work with Nokia. I doubt Nokia wants to "get into bed" with US networks unless they've since changed their ways.

Which they partially have. Companies like Apple have been successful in pushing a device that doesn't compromise much on the device (e.g. network centric branding). Though part of the app store rejection due to bandwith usage is indication that there's still some network influence. And companies like Google are pushing for unlocked phones. If this momentum continues then I can see Nokia being interested in the US market again.