If Skyward Sword sold 20 million copies it would save the Wii from its current downward spiral allowing them to take next year as leading console. It would also make a Zelda title on 3DS and WiiU a higher priority for Nintendo which would mean a large increase in resources and the titles would probably get launched much faster.

But as other users have stated it is impossible for Nintendo to sell 20-million copies on Wii. WiiU will mark the near end of Wii and software sales on Wii will drop even further once the other competitors launch systems. Wii software sales have been very low in the past year or so and I can't see Zelda not only being as successful as TP but more successful let alone the most successful Zelda game ever made!

Don't worry. It won't sell 20 million. :D

So many people missing the point of this thread (including me, until Roll explained it). I blame the OP.

It's not as if Nintendo haven't been able to sell 20 million copies of other games on the Wii. It's just that it's unlikely they'll manage to sell 20 million copies of a single Zelda game... on any console. Half that would be a huge accomplishment for the franchise anyways.

Yah of course Nintendo has been capable of selling 20+ million copy games. But not Zelda and if TP couldn't break the 20 million mark then Skyward Sword has no chance in hell with the hardware on the way out and software sales waining. Honestly if Skyward Sword managed to shift 20 million copies it would single handedly turn the Wii's fortunes around the system would again sell large amounts of hardware and could potentially take over the leading market share for this fiscal year! It would also give Nintendo a much needed financial boost!

I was just never interested to follow the OP's lead. :P

I'm guessing it'll sell in the 8-10 million range lifetime.

10m+ is a possibility, but not 20m that's just acorns.