not everybody is a fan. 90% of all customers are just normal customers. Sure fans will get whatever nintendo is releasing but normal customers will probl think about switching to ps4 where they could already play games like witcher 3, final fantasy 15 and co THIS YEAR instead of waiting, waiting and waiting. And its not like those games (ff15, w3, uncharted 4, bloodborne) are inferior to the new zelda game. All those games are absolutly great titles.
Do you honestly think 90% of Wii U owner are normal customers? Wii U is probably 70% owned by Nintendo loyalists and 30% kids that who probably feel tortured by their parents with the Wii U, hence the shit numbers it has sold. Most normal customers didn't see any value in Wii U and jumped on PS4 this gen.