2D Mario (NSMB DS) moved a lot of hardware/software because it was the first 2D Mario game since like 1991 (not counting Yoshi's starring games or Princess Peach).  We were DYING for that game to come out.  Gamers were born on 2D Mario.

On the Wii, it shifted software/hardware because it was 2D Mario on a home console for the first time in forever.

On the 3DS, it moved a respectable number of units but the magic was wearing off.

On the Wii U, it was virtually indistinguishable from the earlier Wii Version that seemed fresh on everyone's mind aside from being in HD (which made it easy to see flaws).  It also didn't show off the system's power.  NSMBU had virtually no "wow" factor.

Most of us agreed that Super Mario 3D Land on the 3DS was a great game, though it was a little on the easy side.  Super Mario 3D World looks like it's going to show off the simple gameplay of the 2D games, the imaginative and creative levels of Nintendo's past, and some awesome graphics to boot.  Games like Halo, SM64, etc. sell because they are great games on top of being system showcases.  Nintendo hasn't had that graphical showcase title that shows off what the hardware can do.  3D World is that game.  It won't impress on a technical level like PS4/Xbox One titles will but for the uninitiated, they're going to see this game running in HD at demo kiosks and be impressed.

*Oh, if it wasn't clear, I agree with you.  Just felt like ranting.

Because on forums those defending the Wii U sales during it's spring/summer drought said wait until August for the comeback to begin, with Pikmin 3 in August, Wonderful 101 in September, WindWaker HD in October, and Mario in November, along with the casual games (Wii Fit U and Wii Party U) and third party support, with Sega's Sonic exclusives being cited.  The problem is that most of those games bombed.  Windwaker HD probably helped the most because of the bundle, Pikmin 3 gave a slight boost, Wii Party U helped a bit in Japan, and others like Lost World and Wonderful 101 did absolutely nothing.  And forget about other third party titles like Call of Duty.  No one bought them. 

Naturally a bump for that game and the shopping season.

It will sell some systems, but this is the kind of game that will appeal to the gamer that is actually buying a PS4 and Xbox One.

3dland would like to have a talk with you. And it is an evergreen title. So yes, SM3DW has a chance in becoming an evergreen and a major system seller. 

This game will move systems. MK8, however, will be the make-or-break point for the system.

The game will sell and it will also move some systems. There are a couple of ADs on TV right now, which should strengthen the popularity of the Wii U not as an upgrade of Wii but a "new" console.
To all people that compare this game to Pikmin or W101 (saleswise), I have an appropriate anecdote:

I remember the time back in June or so when my excitement level for Pikmin III was insane. So during another boring lesson I turned to my classmates (4 gamers in my class back then, 1 PC, 2 Xbox and 1 PS) and gave full scopes about it.
No one knew what Pikmin was. But it started a little general discussion about Nintendo and their franchises, and guess what?
They all turned out to be secret Mario lovers (at some point in their lifes they all played Mario).
So I don't know whether this is representative for the whole gaming community, but it certainly shows the difference in popularity of some Nintendo franchises.
Mario sells because it's Mario (and because the game looks fantastic).

If released when the console has sold about 100mil, its probably already too saturated to make a huge difference.

But, for sure it made a difference. I actually know someone that bought a Wii because of Skyward sword. Though she got Mario galaxy while at it aswell.

it is a system seller. /thread.

Then it will not be a good system seller, 2D mario moves more consoles with the families, 3D mario puts more preassure on more focused gamers. If they are not buying the console for this game I don't see many people buying it at all.