The info in question comes by way of a financial briefing made by Macronix, a Chinese manufacturer responsible for supplying Nintendo with the ROM chips used in 3DS cartridges. “Macronix’s ROM chips are usually supplied to videogame console maker, Nintendo,” said Macronix chairman Wu Miin in the briefing, which was reported by Japanese site Money Link and translated by NeoGaf users.
First, Miin alludes to the NX in his report: the “new generation console” Nintendo plans to release in March 17.
So, it seems clear Macronix will be supplying ROM chips to Nintendo for hardware of some kind.
So even if the NX does run on cartridges, that’s likely just one format that will be available.