re: Is it possible to be an elite high school basketball player.......

Tons and I do mean tons of high school players make their teams and play well without playing AAU basketball.

College is a different story. To play in college you'd better be playing AAU ball today. A scout can go to an AAU Showcase event and see elite talent on every team. At a high school game they might be looking at 1-2 players.

My son is in his 6th year of AAU ball and this is the most implortant year for him by far. He's 16U (rising high school juniors) and they'll get serious exposure to college scouts and coaches this summer. His AAU season is much more important than his high school season. Not only is the competition leagues tougher but his improvement during the AAU season dwarfs his improvement during the high school season.

Edit: To be an elite level high school player you probably need to play AAU. You have to work on your skills and game year round now to play at an elite level.