Third party support would work if third parties got off their asses and actually tried to utilize the technology instead of just creating crappy knock-offs of Nintendo's games, that or just stick to their guns and make normal games and ignore the motion controls, maybe actually try to one up the system makers. Course it's too late now, even if the Wii started to get some great third party support, the "hardcore" gamers would still call it a kiddy system and deny the quality profusely, Nintendo has spent too much of the consoles lifespan making party games, and alienating traditional gamers.

On topic, Nintendo will have to publish it cause they also helped Mistwalker make the game, I can't really imagine they would let someone else publish it, it's also why there is no chance it will get a port. Personally, I feel they should publish it outside of Japan cause it just seems to me like Japan is no longer the consistent revenue they used to be unless its Pokemon or DQ. They might as well release it and get some extra money. Hell, all they really need to do is translate it, I don't think most of the people actually looking forward to the game would mind the dialogue being purely Japanese, that right there would cut down on hiring VA, and studio work, making an extra percentage of any profits in the West, go straight to their wallets.

Edit: It's close to 150,000 untis sold which is pretty good considering Metroid Other M hasn't even sold that many units in Japan yet. Hell, even Demon's Souls was only 2/3rds of the way to that number by this point and most of that games major success is from U.S./PAL region support. Nintendo and Mistwalker would have to be crazy not to release it here, but then again its not like both companies have always made wise decisions...