This video offers quite the list of details for the NBA Elite 11 demo - except a release date. But when it does arrive, it'll offer plenty to play around with in advance of the full game's October 5 drop.
From the narration and other details, we see that you'll be playing "the full fourth quarter of the NBA Finals" - which, with the ESPN presentation and the broadcast team that worked that game, should be a nice treat. A portion of the singleplayer "Become Legendary" career mode will be available, with the opportunity to import that character into the full game.
Given that NBA Elite 11 has completely remade its controls, the demo will also allow you to fool around with your moves in a tutorial practise mode and give you the chance to go back to the old face-button commands if you're not digging the stick set. Finally, it looks like all difficulty levels will be available in the demo.
As for when it arrives, NBA 2K11's demo went out earlier this week; EA Sports MMA's demo goes out September 28. The full NBA Elite title and NBA Jam arrives a week after that. So while nothing's confirmed, it's likely this rolls next week.