If the Wii U is not replaced within the next few years it will.

If VGChartz is accurate with it's 6.3m figure, 3D World will fall short.
On the other hand, 5.5m is beatable.
3D World definitely deserves it more, as much as it lacks ambition.

It should outsell it eventually. They're both great games, though. 

Sunshine is much better than 3D world. But setting that aside, I don't think it has a momentum to sell the extra amound needed to beat Sunshine.

Before I clicked on this thread I was like "Naw man Wii U probably won't even outsell GameCube.", then I saw the OP and I was like, "Good point. It's likely."

It may... On Gamecube. If the release Sunshine on WiiU as well (like what they did with Ww HD), not a chance

so 1,5 millions to go?

if re-release in different format yes!
maybe 7 millions WW.

Yeah i think its possible for sure

Super Mario 3D World is like a whole game of the levels where you lost the water-gun in Sunshine. Since those were the best levels in Sunshine easily, 3D World is much better and therefore I hope it does much better in sales also .

When it released, I predicted the game would outsell Sunshine in the long run and as of yet it still seems like a good possibility!

Will be close but I can see 3D World winning this battle.