In an incredible feat, Nintendo’s own product page has listed NBA 2K18 “No. of Players” as “up to 10 players” (link)
While no additional information is given as to how the game will support 10 players, it will most likely be through local wireless connection or the internet.
At a cap of 10 players, NBA 2K18 is pushing the limits of the Nintendo Switch’s capabilities.
NBA 2K18 for the Nintendo Switch will be released on September 2017