Recently, there has been a lot of speculation that the upcoming Nintendo NX console could ditch discs and return to using cartridges. This has been fueled by patents filed by Nintendo for a disc-free console, as well as a report that the company that makes Nintendo's DS and 3DS cartridges is expecting a huge increase in sales when NX launches.
Speculation is heating up again today, thanks to the trademark filing for Nintendo's upcoming Wii U/NX title The Legend of Zelda: Breath of the Wild. The game's "Goods and Services" description is largely the same as other Wii U titles (covering things like "downloadable electronic video game software" and "electronic game programs"), except that it also lists "video game cartridges" while other Wii U games do not, unless they are also available on 3DS. This isn't confirmation of a cartridge-based console, but it certainly makes it seem more plausible, and that could be a good thing.