A couple of tidbits have come out in the past couple of hours regarding NBA 2K14. On Twitter, Chris Manning mentioned that NBA 2K14 will be playable at the Gamescom convention, which starts today. It is safe to assume that the current generation game will be on display and historically what is played at Gamescom ends up being the public demo before release.
Also, over in the Operation Sports forums, Erick Boenisch has confirmed the return of retro teams in NBA 2K14, saying:
Classic Teams live on my friends.
With the publicly playable demo available tomorrow at Gamescom, be sure to keep tabs on us here on the main site and in the NBA 2K14 Forum to keep up with all the information available.