He can head off to one of the better title contenders and take a veteran-minimum to try and win again. He doesn't want to do that, by all accounts it goes against his principles.
He can retire. But then, if you try barking, yelling and clapping in the face of small European men you see at the post office, you get in a lot of trouble.
Or he can return to the Celtics. And indications are that that's the most likely scenario. From the Boston Herald:
The Celtics would love to learn Kevin Garnett's plans, hopes and desires as soon as possible, but according to sources close to the situation, the Hall of Famer-to-be might be waiting on the team.
By all indications, the Celts have made it clear they want Garnett to return for at least the 2012-13 season, and there is strong evidence from those involved that he is more than willing to discuss that possibility.
via Situation must be right if he is going to return - BostonHerald.com.
The trick here is that if Garnett's coming back on a short-term, small-money contract, which is what the Celtics will want and need, he has to know the team is going to contend. But the Celtics are purposefully looking to the future. They're angling to move up in the draft, have Jeff Green coming back, and will be looking down the line. They want Garnett back, but not at a huge price.
At the same point, you can't blame Garnett for wanting a sizeable contract. He was a Defensive Player of the Year candidate this season and played tremendous basketball in the playoffs. He was the playoffs MVP for about six weeks. He showed no signs of slowing down until the fourth quarter of Game 7 vs. Miami.
It's a big complication of priorities for both the team and Garnett. They want him back, but they don't want to pay out the nose for him, nor commit long-term. Garnett wants to be respected, and wants to compete. Loyalty's important. Respect is more important.
Garnett's future could be the most interesting component of the summer behind Deron Williams.