Bosh is available to anyone who would take his contract and give a top 59 protected pick. He probably won't play again and the Heat have to be terrified he drops dead on t.v. during a game. If they could get out of his contract, I imagine the Heat would be thrilled.
No he isn't or he wouldn't be on the Heat. Either he plays or Miami gets to write off his contract for a medical retirement.
"Write it off" isn't what happens, you realize. They'd get salary cap relief next year, after having a dead roster spot this season. They'd also have to pay him about $34.9 million over the life of the contract, with insurance covering about $41 million. That's a lot of money involved, even for an NBA team.
Not to mention, if Bosh plays for even a second and then decides he can't do it, then the Heat are out even more money, and the cap hit would happen next year as well. Furthermore, if, after medically releasing him, another team's doctor's clear him to play, and he plays in at least 10 games, including the pre-season, the Heat would again be on the hook for his full salary, including the cap hit.