Wii Music has way too much negative hype in my opinion to be a huge seller. Obviously won't repeat such sales as Wii Play and Wii Fit who had lots of hype. Although the brand will sell the title and I'm thinking after release it'll have more positive reception to help sales. So Wii Music is probably looking at about 5 million in its lifetime.
LBP on the other hand is the exact opposite. It has loads of positive hype and lots of advertising. However it doesn't have the benefit of a huge brand like Wii Music nor is it guaranteed to catch on. My guesses for LBP is about 3-4 million in its lifetime.
Now it seems I'm suggesting that Wii Music will come out the victor when it comes to sales but I'm not guaranteeing that. But LBP still does have a chance.
Personal note both titles I feel about the same. They are both interesting concepts but I"m trying to wonder will I have time to spend all that time in creation. I really like to enter games that just startup and go and unfortunately that doesn't mean 50 single player levels in LBP or a set list of songs in Wii Music doesn't warrant the purchase.
