This informative article in the Miami Herald discusses the issue. The Heat will certainly benefit handsomely. Marc Ganis, a well known sports business consultant, suggests that the Heat can probably sell out the upper deck in the arena - typically closed in the past - and realize an increase of 4000 in average attendance. At $45 per ticket, that's $7.4 million in additional revenue. The effect on attendance revenue is likely bigger, however, since the Heat can charge higher prices for existing tickets than it otherwise would have. Sponsorship deals will also be more lucrative.
Most businesses surveyed in the article suggest quite modest indirect effects - statements which cast doubt on the economic development pitch perennially made for stadium subsidies. One firm however, is clearly in line for a windfall. The Sunshine Network signed a long term, exclusive contract with the Heat in March. Their advertising revenue will soar, but the payment to the Heat was negotiated without the Shaq effect in mind. How does the Network feel? "We're giddy about Shaq." As are Miami basketball fans, I'm sure.
The trade changes the NBA landscape, which I find quite interesting. Next year's title is up for grabs.