It`s still very much possible.
Wii U`s flaws are still here and until they get corrected things won`t really improve. But when they do, Wii U will outsell GC.
GC had what Wii U hasn`t really got so far: games for the Nintendo fanbase and core gamers in general.
Last year`s line-up only had Mario 3D World and a WW port. Wii Party U and Mario and Sonic were/are for a market that so far doesn`t know that Wii U is not a add-on to Wii. o, no wonder those games didn`t manage to do more. I believe that even Mario 3D World could have done more if that market was there (even if in smaller numbers than on Wii).
Honestly, until Nintendo can get a good, steady release schedule, it`s fanbase will opt towards the PS4.
Not saying it will do much better than GC, but they can surely outsell it if they can get their act together.
