NSMB is a very popular series, with more potential for growth. NeoGAF's naysayers are extremely unaware of are the following points; I will address them here.
Many on here are extremely ignorant of their 'Evergreen' approach, which was more since the 7th Generation. That is to say that these games aren't titles which everybody typically buys on Day One, although some will - They are rather games that will continue to sell for the duration of the console's life cycle and beyond (thanks to backwards compatibility and digital distribution), and will most probably be on the 'must play lists' for those who bite on their games consoles. I am not saying that they will reach the same heights. I am rather suggesting that it is better to wait until the 9th Generation consoles release before writing anything off - To do so at this point is extreme folly and abysmal form. It's also rather bizarre, preposterous and dumb.
NSMB2 is actually a faster-selling entry than the record-breaking DS game. In 2008, two years after its release, NSMB on the DS had sold 5 million copies Worldwide. In 2009, it had sold 18 million; that's a further 13 million copies, and without a price reduction - I think you can agree that this is a beastly level of growth for ANY game in its third year. Every development and publishing house in this industry would give limbs for that, and more. Since 2009, it has sold over 12 million more copies, and in March 2013, we learned that it had eclipsed the 30 million mark. That game has been out for over seven years. I would put it to you again that every publisher in the games industry would give their limbs and the entire kitchen, not just the sink to have games perform as well as that from their fourth year onwards. Now, consider that NSMB2 has been out on the 3DS for just over a year, and launched on a system with a higher user base than the Wii U has currently. Consider that NSMBU hasn't even been out for one year, that it launched about three months after NSMB2, and is the only entry which was a launch title. Now imagine what is possible for both by March 2019.
Furthermore, 6.42 million was as of March 2013, and eight months after its launch. We know that since then, the 3DS replaced the X360 as the best selling console in North America, and the game still sells now. Not so unthinkable, then, that when the 2DS launches, and as more people buy a 2DS or 3DS, or when both hit that £99 point of entry, more people might want to play that game once they've bitten. For the third time, I would put it to you that every developer and publishing house would LOVE to be in a position where their games can provide plenty of bread and butter over long and often challenging stretches.
Simply put, what these games accomplish on a single platform is nothing short of outstanding - NSMB is bigger than COD and GTA in those respects, and that's why I laugh hard in the faces of those who spew the Doom Narrative. It isn't about one week's worth of sales for Nintendo. It's about the long haul. 6.42 million without an official price reduction is still a hell of a lot more than what plenty of games ever accomplished across the PS360 consoles combined, breaking even at lower number barriers and achieving more than enough to justify new entries.
Oh, and NSMBU is a lot closer to Super Mario World than SMB3. On a personal note, I would hope for more in the way of Switch Palaces and secret exits, levels and stages. I would also hope that future handheld versions have the Koopalings, or more bosses such as Mouser, Tryclyde and the Reznors. If the trailers are anything to go by, Super Mario 3D World appears to be delivering heavily in this area.
Now, to address the art style - I don't understand why these games are beaten with this stick on the Internet, and feel that this is very much undeserved. As far as I've noted, very few say this about Super Mario All-Stars, which, to my mind, is a very similar case. I don't disagree that a new art direction would be welcome, but these games are primarily a throwback to the originals, and above all... they're STILL lots of fun to play!! They're also more about the level designs, which are, for me, some of the tightest in the 2D series, especially in NSMBU. Each of the NSMB games plays differently, too, but it appears that few can actually look beyond the art style to think about that, and I feel that this is unfortunate. Let us hope that Super Mario 3D World's showcase will provide even greater platforms for more ideas to be realised in future NSMB entries.