Here's the analysis that should be performed prior to rejoicing about bringing the NBA back to town:
First, estimate how much revenue (through all channels) the team will bring to the area, specifically to entities other than the team's ownership, each year. Next, multiply that figure (plus inflation) by the number of years it took for Key Arena to go from bring the crown jewel of the NBA to no longer a viable venue. Next, estimate how much money the city will be required to contribute to the cost of the new arena that the NBA will try to racket them into building the next time around, assuming that period of time is similar to the "lifetime" of Key Arena.
Does the revenue outweigh the cost of the next arena? If so, bring 'em in. If not, bring 'em in anyway, but don't bitch and moan next time the team gets purchased by a tycoon from another city that wants a piece of the action.
Remember how you felt when you realized the Sonics were going away? That's how the fans in Sacramento are feeling right now. Why is that OK? Why should we not expect the same racket when the new arena becomes outdated?
Lots of problems with the formula used here. 1) It is virtually impossible to put an effective dollar figure on the revenue a sports team brings to an area. It is very similar to trying to figure out how much sport fishing dollars impact an area.
Next, Key Arena was never the "crown jewel" of the NBA. Older folks here will remember that Ackerly had his own site and wanted to build a new arena before Key Arena was renovated but for several reasons it was not done. So, Ackerly went along with the city and they renovated Key Arena but even when it was finished it was a middle of the road at best venue.
While it my be splitting hairs, the two situations involving the Sonics move and the Kings move are quite different. The Sonics had a 40 year history in the city and enjoyed good fan support. The Kings have been in 4 different cities throughout their lifetime. Clay Bennett paid lip service to the area after purchasing the Sonics and as many emails made public have shown, he never intended to keep the team here. The Kings owners are broke and the city of Sacremento is broke, shortly after forging an agreement this last summer both sides figured out just how broke they were and the deal fell apart. The Kings owners take the heat for backing out of the agreement but both sides know the other side doesn't have the funds to carry out the deal, and like Tod said, they have been at this for 4 years.
Finally, Stern is getting very close to retiring and the big spot on his legacy is the moving of the Sonics franchise. He helped broker that deal and in hindsight it was a terrible PR move for the league. He wants to put a team back in Seattle but the current economics of the league do not allow for expansion, therefore, the easiest way to do it is to move a struggling franchise to Seattle.