Apparently, this is all speculation, though, as a Nintendo rep told Eurogamer that these tidbits of info are nothing more than rumors. "Nintendo has not announced any further information on Mario Kart," the rep said. "We've spoken to the magazine and it's just pure rumour and speculation on their part." So while Nintendo shoots down all of this info, you can still be sure in betting on the track list being a mixture of older tracks, with some new ones sprinkled in for good measure. We'll just all have to make our own guess as to how many there will be.
Read - GoNintendo leaks info from upcoming issue of NMag
Read - Nintendo tells Eurogamer it's all rumors