https://arstechnica.com/gaming/2017/12/big-titles-must-wait-as-nintendo-pushes-back-64gb-switch-game-card-rollout/

Those wishing for 64GB Nintendo Switch game cards will have to keep waiting. According to a Wall Street Journal report, Nintendo pushed back the rollout of 64GB game cards until 2019, citing "technical issues" as the problem. Game developers get Switch cards from Nintendo, so this means that they'll have to wait to get game cards that can support big titles.