One of the Wii U's biggest supporters, Ubisoft, has stated that they will not produce any more Wii U exclusive games until more consoles are sold. At Present the Zombi U dev simply can not justify development of any exclusives due to the small revenue gained from Wii U exclusives. However games like Watchdogs, Assassins Creed and Just Dance will still make it to the struggling console this fall, so support for the Wii U is not being dropped all together.
Source Courtesy of Veho