The Wii version of Just Dance 3, released last year, has sold over 9.5 million copies to date. It's the best-selling third-party game on Wii. Skyward Sword, released about a month and a half later, has sold under 3.5 million copies to date, just over half its predecessor's (Twilight Princess) LTD sales.
Mario Party 9, released this year, has sold about 550k in America. Xenoblade Chronicles and The Last Story, both released this year in NA, have combined for about 420k sales in the region.
I don't know why people insist on believing that Nintendo has lost the "casual" audience, unless they're the sort of people who consider Zelda, Xenoblade, and The Last Story "casual" experiences. Because it's pretty clear to me that the games traditionally considered "casual" are still selling quite well on Wii. At least, they're certainly selling better than the games traditionally considered "core," which makes it pretty clear to me which audience has actually abandoned the Wii.
