Pat Riley now has his big three, and while it still hurts the hearts of Cleveland Cavailers fans, everything is going to work out, as a number of salary cap rules have now come into play that will help the heat get all big three starts signed, and all three teams still have cap room to add other pieces. The Toronto Raptors and the Cavaliers also got trade exceptions in return for the sign and trade deals that allowed all of this to get done. This is pretty technical, confusing stuff, but I will attempt to break down the jargon.
The first move was to resign Dwayne Wade, since he was already a member of the Heat, they can use the Larry Bird exception to sign him. That means they can go over the salary cap without penalty to resign their player. That means Wade can be paid a lot more money.
In the case of Chris Bosh, he was signed to a deal with his Toronto Raptors and was then traded to the Heat for two first round draft picks. The Raptors also get a trade exception that allows the deal to go through even though the salaries do not match.
Under NBA rules trades of players must have matching salaries. So the Raptors get a trade to add the salary that was lost on Bosh. Bosh also gets to sign a bigger deal than he would have had he signed with Miami straight up. Since he does not have the endorsement deals that Lebron James and Wade have he will likely be the highest paid player in South Beach.
The Cavaliers entered into a similar agreement with Heat, and will get the rights to five future draft picks and a similar exception to add salary within one calendar year. Essentially the Raptors and the Cavs can now go out and add big time money to their payroll, and have one year to do just that.