Orlando is going to want an all star, promising young players, picks, and cap relief for D Ho. Miami can easily offer this to them. Miami gets Howard and is stuck with Turkoglu for the next two years. They give up Bosh, Joel Anthony, Norris Cole, Mike Miller, who would probably retire, and two #1 picks.
Miami would basically ensure them the Finals for the next half decade, at a minimum. Orlando would get an all star in Bosh, who they could use or move for more assets and cap relief, two solid players, and picks. It would be a better package than Houston's offer. Bynum won't sign an extension there, apparently, so LA isn't an option unless Houston facilitates the deal and Bynum agrees to play there.
This would be a total gangster move by Pat Riley. Dwight Howard patrolling the paint at both ends, surrounded by LeBron, Wade, Battier and Ray Allen, would be a ridiculous team to defeat.