Wii U can’t transfer data to another Wii U
You can’t transfer games and purchased DLC between Wii U units right now. So if your Wii U gets stolen or you sell it for whatever reason and get another one after that you will lose all your purchased DLC.
Transferring data from one Wii U to another Wii U is not supported at this time. However, we are looking into this feature and will provide an update if there is anything to report.
Transferring data from one Wii U to another Wii U is not supported at this time. However, we understand that this is a feature of interest to some consumers so we are taking that into consideration and are looking into this feature.
The 3DS didn’t have the 3DS-to-3DS transfer feature on day one either. If I’m not mistaken I don’t think that feature became available until a December 2011 system update.
I don’t think Nintendo will allow this to go missing for long.