In one month, on March 27th, 2023, the 3DS and Wii U eShops will permanently cease new purchases on games and DLC. We're very sad.
However, today (February 27th, 2023) actually marks your last opportunity to purchase Fire Emblem Fates, as Nintendo will be removing it from the eShop store on Tuesday 28th February, one month prior to the full closure.
As a reminder, the reason for this is to allow new players ample time to reach Chapter 6 within the game, at which point you'll be able to choose one of three story paths: Conquest, Birthright, and Revelation. The corresponding DLC will then be available to purchase up until March 27th, 2023.
For those who might be on the fence about getting Fire Emblem Fates, we'd highly recommend experiencing it. In our full 9/10 review, stating that "Fire Emblem Fates does a remarkable job delivering what newcomers and long-time players both could possibly want out of this series".