Nintendo eShop for Wii U & 3DS is being discontinued next year, funds can't be added starting next month
The end of an era...
Unfortunately, the Wii U and 3DS eShop pages will soon see their demise. Starting on March 27th, 2023, you will no longer be able to make new digital purchases on the last-generation consoles. The ability to add eShop funds will end even sooner, with the feature set to be unavailable as of next month, on August 28th, 2022.
Fire Emblem Fates in particular is getting an individual shut down time, February 28th, 2023, one month before the entire eShop goes kablooey. Its DLC will be available until March 27th, 2023 though, as with the rest of the software on the eShop. Make sure to download any digital-only games and DLC you want before then, and prepare for the prices of physical Wii U and 3DS games to skyrocket.
Of course, all previously made purchases from the Wii U and 3DS eShops, including any games and DLC, can be redownloaded at any time, even after the closure of the service. Software updates and online play will continue to be available as well.