The single greatest thing that could happen to Zion's career is to become the second banana. Going to a team like Detroit where Cade would take all the heat/pressure and be the #1 offensive option would be huge for Zion. Take all the pressure off of him and just let him cook.
There are no salary cap implications. There was a clause in his current contract that required him to play a certain amount of minutes per year or else his contract lost its guarantee. He did not play enough minutes last year and that clause kicked in. You can cut Zion today and not owe him one cent and not one cent would count on your cap.
Availability is an issue for sure, but not the biggest one. The biggest issue is his passion for the game. You can get him 100% healthy, you can put him in a great position, but if he doesn't want to play the game, well something about leading a horse to water.