There is no way in hell, the hellishly hellish hell, that FFXV could run on a Wii-U...no way AT ALL.
In the first few photos you showed with Leviathan and the other Snake thing...the Poly counts are enormously different, the scale of the serpents is insanely different. The observable texture detail is enormously different. All better on FFXV.
FFXV has a dynamic weather system (Wind makes a difference by whipping up dynamic sandstorms, Rain makes physical puddles, etc.) There is a day night transition with physical objects in the sky instead of just a series of textures painted on a rotating orb that surrounds the game world.
There is a TO CORRECT SCALE world map with TO SCALE vehicles, including massive airships (a few examples of such airships were seen in the trailer)
All of these things take a MASSIVE amount of memory, to which the Wii-U does not have. Not to mention the lack of power in its GPU. I could go on and on.
what i'm saying, in order for this game to be on Wii-U, the entirety of what makes the game awesome, would virtually have to be scratched.
Not to mention, Nomura said it is his utmost goal to make the game run at 60FPS @ 1080p.
...uhh...ill just put my favorite quote of all time here.
"Welcome to Pain, the second of three...You have dealt the first...now deal with me!!"