I know the site has guessed correctly at stuff before, but I'm not buying this.
Firstly, making a new version of the console so soon- with superior capabilities- would be shooting themselves in the foot. The console is already selling poorly, but this move would mean any of the original units left unsold would basically have to be written as people would simply wait for the new one. Nintendo would have to basically re-manufacture a new (and probably more expensive) console all over again to keep up with the current level of demand.
Also, I'm not even sure how a circle pad peripheral would work. Keep in mind that Nintendo "add-on" rumours crop up very often. In the last days of the GBA magazines were confidently reporting that they were going to release a peripheral to increase it's graphical capabilities, and the Wii had been dogged with similar rumours about a HD upscaler for years (although third parties did actually make those) before the Wii U was announced.
As for the "lack of 3D" thing, this sort of illustrates how internet rumours go through a chinese-whispers series of embellishments. This morning the rumour was that Nintendo was simply rebranding the console, including a name change, to downplay 3D, presumably to get away from the "3D will melt your eyes" stigma. Now the actual console is being altered to lessen the capability?
(Incidentally, since you can already turn it off any time you want I fail to see how they could do this short of removing the ability completely).
So what's really going on here? Using the Wii U as an anology ("Wii U is much more powerful than the Xbox 360" actually meant "Wii U is about as powerful"), I'm guessing Nintendo is just going to refocus their marketing to downplay the 3D aspect of the console. Possibly there's a 3DS lite or equivalent in the works, but I'm not betting on the circle pad thing being true.
