I always thought it would be cool having a career mode that lets you start with a created player and work your way up...from High School.
So you could go into the draft early if you were THAT good (should be a very hard thing to do in the game). Or you could choose to go into a college. Or maybe you could go to Europe instead.
What would really help with this would be to have historical teams at least on the NBA level. Would be better if it was also true in college level. For High School level, I find it impossible to do.
Players could truly experience the fear of facing Jordan or see someone like LeBron smash everyone in High School.
This mode seems to be almost an impossibility tho, since getting license for all those past teams should be hard. Not to mention the sheer amount of data involved.
Even if the high school part and the college part was fictional, it would still be kind of fun.
General small changes
-Very flexible ratings determined by every game played. (If someone plays a bad game, or gets injured, the ratings DROP)
-Realistic trades
-Historical teams
-International teams
-National teams