Ubisoft was Nintendo's biggest third-party supporter when the Wii U was released. The support has grossly waned since then, which was marked by Ubisoft's sudden announcement to make Rayman Legends multi-platform instead of a Wii U exclusive. In an interview with Kotaku, Ubisoft president Yves Guillemot said that Nintendo has to sell more units if they want more exclusives from the company.
"We need more sold," Guillemot said bluntly. "They are coming with five of their biggest brands ever. And the yen went down. So maybe they will take steps that will increase the number of consoles sold."
Ubisoft isn't cutting ties with the console completely. They still plan on releasing Wii U versions of Assassin's Creed IV, Just Dance, and Watch Dogs.