It's been seen and rumored that customers that purchase a used Wii-U from retailers and create an account on the console can re-download any games from a previous account that was on the console. This possibility is due to the fact that the Nintendo Network ID's are associated directly with only one console and not used on any other Nintendo devices such as the Wii or Nintendo 3DS. This rumor was started when a NeoGAF user purchased a used Wii-U and created his own account on the console. Upon creating the account he was able to download Nano Assault Neo and Trine 2 free of charge from the marketplace.
So far we've heard no statement or comment from Nintendo regarding the issue. Whether or not Nintendo will be able to fix this error is unknown due to the fact this could be built into the hardware itself or possibly built into the marketplace and software changes need to be implemented. More news and statements regarding this rumor will be shown as soon as we hear anything from Nintendo or other users who are benefiting from this.