They've had this a couple of times, and the last attempt I remember was the failed Shaq vs Dream, Kenny Anderson vs Nick-at-Nite and I forget the 3rd player. It was supposed to be somewhat like a boxing match, with the game divided into rounds or something like that. But still, the biggest names have to be involved, which most of them won't.
2-ball was good, the 3-on-3 was good, they've now turned the Skills Challenge into a farce, but these were still simply all warm-ups for the big game. And without the game, the entire weekend is a wash.
Nothing matters if the players are not motivated to play. A tournament with 1 mil, for dudes making $700K a game is not going to change their motivation. And no one is going to want to play 1-on-1 AND the All-Star Game.