Definitely a new non first person Metroid game for the Wii U.

Shenmue 3, or at this point, Shenmue (complete).

Suikoden VI

A "realistic" Zelda U.

Since obviously no one in here knows the correct answer I'm just gonna say it.

Knack 2.

The games that I am longing most for at the moment would be:

Zelda U
The Last Guardian
Uncharted 4
Banjo Threeie

Also SOMA looks to be an interesting game. I really enjoyed Penumbra and Amnesia.

X on Wii U right now. Kingdom Hearts III on PS4.

Not much else unknown on the horizon right now JRPG wise.

Anything from Namco, Level 5, etc. New Suikoden, Wild Arms, Ni no Kuni, Breath of Fire, Star Ocean, Tales, anything like that for PS4.

XB1
Jade Empire 2, Kameo 2, Kotor 3, Crackdown 3, Phantom Dust 2, Halo Wars 2, Killer Instinct Season 2, Forza Horizon 2, MechAssault 3, Project Gotham Racing 5, Perfect Dark anything, Viva Pinata 2, Shadow Complex 2, Bloodwake 2, Crimson Skies 2, Alan Wake 2, State of Decay 2 or MMO, Ryse 2 & Battletoads anything.

PS4
Uncharted, Mark of Kri 2, Syphon Filter 4, Rival Schools X, Vagrant Story, Dark Cloud 3, Okami 2, The Last Guardian & Fear Effect 3.

PS4/XB1:
Shenmue 3 announced, Mr Driller X, Tenchu X, Darkstalkers 4, Virtual Fighter 6, Beyond Good and Evil 2 & Legacy of Kain.

Pokemon MMO
FFVII remake
FFVI remake for Vita
Jak and Daxter 4
PS4 exclusive Crash Bandicoot
PS4 exclusive Spyro

only these games:
Megaman Legends 3
Megaman x 9
valkyria chronicles (3 or whatever)
advance wars
heavenly sword 2
Mario party 10 WITH online

Metroid Prime 4

And imo, a StarFox/Metroid crossover would be ruining both franchises.

Chrono Cross, Chrono Trigger DS. There you go, you get both.

Just one of the following would do it:

Half Life 3
Fallout 4
New Red Faction
New Timesplitters
Battletoads
Banjo-Kazooie
Conker
Jumping Flash reboot
Starhawk sequel
Starfox Universe
F-Zero UX
Mother 4
New Metroid
Pokemon proper on Wii U
Any classic PC strategy series re-imagined for Wii U
ZombiU Part Deux
Red Steel 3
No More Heroes 3