Just saw this in a random Japanese chat tonight.
http://www.nintendo.co.jp/support/in...2014/0227.html
The article politely thanks everyone for their continued support and long-term usage of their services but they have announced the termination of service for May 20 2014. It does not make any reference to regions so it is not clear if this is exclusively Japan's region only, or worldwide.
For amusement I saw comments in the chat about this such as "campaign to force Wii U" and "Nintendo sucks" so it seems they have a bad taste in their mouths about it just like, well, the rest of the world probably will.
EDIT: Courtesy of the post below, worldwide discontinuation has been confirmed.