Best Buy and GameStop have updated their product listings for NBA 2K18 for Nintendo Switch including a new box-art which mentions the requirement of an Internet Download and a microSD card.
This is the first time we’ve seen a description like this mentioned on the box-art of a Nintendo Switch game, which could indicate that additional content must be downloaded in order for the game to run. NBA 2K18 will indeed be available in a physical format, however, it is possible that the game just needs more space than what the cartridge offers.
NBA 2K18 will be available on Nintendo Switch on September 15th for $59.99.
Source: /r/NintendoSwitch