IGN picked Okami over Zelda? Without having read the article, that doesn't make much sense, but I digress.
I think what you described is a best case scenario. It certainly is possible, but not necessarily a sure thing. The similarities the two games only go as deep as what you mentioned. They aren't being made by the same developer, they aren't the same type of game, NMH won't be filled to the brim with Japanese mythology, the mood of the games will likely be different, etc. With that being said, NMH stands with Nintendo's big 1st party games as the ones I am anticipating most for the Wii. I would love if your thoughts and predictions came to pass.