As more people keep seeing that multi-platform next gen games are announced for Xbox One and PS4 and NOT the Wii U I think this will hurt peoples decision to pick one up. It is really only the first YEAR of 8th Gen consoles and already the Wii U is being left out. MK and SS will help keep ok sales.. but nothing spectacular. The Wii U is quickly becoming a "last gen" console.
I think this reason alone will be why the Xbox One will outsell the Wii U in 2014.
XBLive: cpg716 PSN ID: cpg716 Steam: Luv4Tech77
Predictions on 12/01/15 - Generation 8 Totals:
PS4: 85-95m
X1: 55-65m
WiiU: 20-30m