wii's 3rd party lack of success...could it be an isse on the long run?

[Spectrumglr]

ok, Wii is selling like hot cakes (probably even at a higher rate than VGChartz's reports as NPD July sales figures were 18% higer than VGChartz) and clearly by the end of the year it will be the N°1 next-gen system by a great margin...but still there's a lack of support by 3rd party devs and not without a reason as 3rd party games are selling poorly (compared to the user base). Could this be an issue for the HW sales in 2008? How long can continue a success that's only based on 1st party games?