I'm going to quickly go over the points and respond.
7. The Wii
This is just a sensational claim to try and suck people into the article.
6. The Virtual Boy
No list of Nintendo's mistakes is complete without Virtual Boy. That said, I agree with others who argue that it didn't have a big impact on Nintendo overall - Game Boy continued to be popular. I'd argue N64 and maybe even GameCube were bigger problems for Nintendo's business as a whole. Definitely worth mentioning, but its overall impact was small.
5. Online gaming
There's no doubt that Microsoft dominates the online console game market. There's also no doubt that PS2 outsold not only the original Xbox, but also continues to outsell the Xbox 360! I'm not saying online gaming is unimportant, but there's one feature on the console market that is definitely moving systems right now and it's not online gaming - it's wand-waggling.
Online gaming is important, and Nintendo isn't denying that. Maybe it should be pursuing a more full-featured, convenient online model, but, again, I point out that such a model is not getting Microsoft anywhere right now.
4. Censorship
This was definitely a problem for Nintendo back in the day. The company's "kidsie" image still hounds it to this day, to the point where a lot of people still assume that games like RE4 are being censored by the big N. On the other hand, Nintendo's family friendly approach is currently allowing it to score big hits with products like Nintendogs, Brain Age and Wii Sports.
Still, Nintendo's one-time censoship had a major impact on its last three consoles and its image in general.
3. Third parties
I'd argue that this is the best point in the article. People think Square moved to Sony because Sony had CDs. If so, why didn't Square move to Sega Saturn instead? Answer: Nintendo and Sega were both raping third parties with massive liscensing fees (hyperbole, much?

) not to mention various censorship and other third party control issues Nintendo had.
Sony knew this was a weak point for Sega and Nintendo and fully exploited it. No doubt CDs helped Sony vs. Nintendo too, but Sony's lower liscencing fees and "do what you want" attitude made a difference. Ironically Sony is starting to become more restrictive - eg. all PSP games must have exclusive content.
2. Nintendo 64
A lot of the article's points about N64 seem like a rambling fanboy rant. Things like the controller may have been quirky, but I don't think they had a huge impact on Nintendo's sales like the vanishing third party support did.
The lack of CD ROM definitely hurt Nintendo, Square probably wouldn't have switched teams if Nintendo had included CD ROM, and supposedly Square encouraged other third parties to leave as well. As I stated above, I believe there was more to it than just CD ROM, but that was certainly a key point, if not THE key point.
1. Nintendo Snubbing Sony
This is definitely one of the most speculative points: many things could have gone wrong if Nintendo had stayed with Sony...but I must admit that I think N64 could have "taken" Sega Saturn if there'd been no other competition. I think Sony was definitely on the ball with Playstation on several points such as marketing, third party relations and ease of development.
That said, who knows if N64 would have been what it was if Nintendo had gone thorugh with its obligations to Sony? This was a big mistake, but who knows what was down the other path?