Uhhh...did everybody forget that Nokia still exists as a company? And that as part of the sale they are only barred from selling mobile devices for 3 years? Why in the hell would they want to build positive rep for a brand they will be most likely competing against in a few years?
Frankly the whole argument is moot anyway because you go into mobile stores and folks don't call it the "Nokia Lumia" anymore than they call it the "Samsung Galaxy" or "HTC Evo" its just the Lumia, Galaxy, and Evo. Working retail I deal with folks and phones all damned day (one of the new services I offer is loading Android ROMs,becoming quite popular here) and I can tell you nobody calls them the full name, they just call it by the model.