One really big thing that Wii U failed at was having a steady advertising/marketing campaign, it would have a big game to advertise then go 4-6 months with nothing major.
Nintendo really needs to capitalize on launch/Zelda (March), Mario Kart (April), ARMS (Spring), Splatoon (Summer) releasing in quick succession and have a solid 6 months of constant advertising.
When the herd loses its way, the shepard must kill the bull that leads them astray.