With the imiment release of Playstation 4 and the next Xbox, along with a slew of incredible next-gen titles that will not be coming to Nintendo's console, I say it is fair to predict that the Wii U will finish last in sales for the 8th generation.
After scanning the forums and seeing responses from the Nintendo faithful on topics involving graphics and multiplats (both from Western and Japanese developers), I can also say it is fair to assume that almost everyone who bought the Wii U is currently going through some form of buyer's remorse. A sudden stream of first-party games for the system may ease that remorse, but it will not be enough to spark any highlightable growth in hardware sales.
Let's break down the releases which will be on the Playstation 4 and the next Xbox but not on the Wii U:
The Witcher 3
Star Wars 1313
To further demonstrate my point that the Wii U's future software will not have enough fire to ignite a sizable upward trend in sales, let's break down the Playstation 4 exclusives:
Killzone Shadow Fall
Infamous Second Son
Final Fantasy XV
Now let's consider 7th generational multiplats and exclusives that have yet to be released but will not arrive on the Wii U:
Grand Theft Auto V
Metro Last LIght
The Last of Us (PS3 Exclusive)
Metal Gear Solid V
Beyond: Two Souls (PS3 Exclusive)
Lost Planet 3
Dead Island Riptide
Saints Row IV
Let's be clear here. The Wii U currently lacks an arsenal of killer titles, and when you see forum members claiming their most anticipated game for the platform is LEGO City Undercover, it becomes more and more apparent that the system is in a terrible spot.
If we look ahead, other than the first-party Pikmin 3, only Ubisoft is really extending support to Nintendo's console. And with the same games (Assassins Creed IV, Watchdogs, Splinter Cell Blacklist) available for true next gen platforms with much more realistic visuals, it does not seem that the Wii U will be able to suddenly reverse it's terrible sales numbers.
Taking E3 into account, Nintendo should come out with guns blazing as far as first party titles are concerned, but I do not see a Mario, Zelda, or Super Smash game being released in 2013. Instead, there will be a HD remake of Wind Waker.
Now, all the Nintendo faithful need to stop being butthurt and come to terms with their decision to buy a Wii U without considering the games release calender. And if they continue to argue that software will sell consoles, they cannot compare the Wii U's upcoming games library to that of the Playstation 4, the next Xbox, or the current Xbox 360 and Playstation 3.
TLDR: Nintendo did not effectively plan it's first party release schedule for the Wii U, and upcoming Wii U games will not suddenly drive sales for the system.