Releasing game footage at this time of year always looks more like the previous year's iteration than it does something new, so the 2K13 footage I saw definitely still looks like NBA2K12.5 at this point.
With that said, the dunk contest threw me for a major loop. Have you ever wondered what Guitar Hero would be like if instead of the buttons controlling musical notes, they controlled the process of a slam dunk? Nope, me either, and for good reason. However, apparently 2K thought that'd be the best way to put together a dunk contest for 2K13: http://www.youtube.com/watch?v=-A1wlCcJ4f4#t=1m48s
I do not support this.
But again, to go back to the actual gameplay, I would definitely take any footage with a grain of salt. The 2K guy surely blew a lot of smoke, but he's being truthful in saying they're right in the middle of the development cycle, so things are still very much in progress.