The chance that the Oakland A's will end up in San Jose is almost zero. The reason: the San Francisco Giants own the territorial rights to the South Bay, which means all other major league baseball teams are prohibited from moving there. There's been some suggestion that the A's could work out a deal with the Giants, just as the Baltimore Orioles did with the Washington Nationals, but that's highly unlikely for some very specific reasons.
First, the Giants situation is different from Baltimore on several key issues. The Orioles' territorial hold on DC was always tenuous. So it was no surprise that when the Montreal Expos moved to the nation's capital, the two teams were able to work out a revenue sharing deal. By contrast, baseball Commissioner Bud Selig has affirmed the Giants' absolute rights over San Jose.
But more importantly, allowing the A's to move to San Jose could bankrupt the Giants. The reason is that a significant number of the Giants season ticket and luxury box holders come from the Peninsula and the South Bay. If the A's were allowed to build a new ballpark in San Jose, the Giants would likely lose many of those well-off fans.
Normally, some compensation might grease the skids. But the Giants are anything but a normal professional sports franchise. They're in a extremely fragile situation financially. They have the only stadium in the country financed entirely by private funds (minus the free land they got from San Francisco). As a result, they have a huge debt payment each year to cover the original loans they got to build AT&T Park.
Moreover, the team's attendance has been lagging of late, and there's no indication it's going to rebound soon. Since Barry Bonds' departure, the team hasn't had that big box office draw.
There's no way that Major League Baseball or the Giants' owners would allow the team to go bankrupt just so the A's can get the stadium of their dreams in the Bay Area. And if the A's were forced to fully compensate the Giants for the team's lost revenue caused by a new ballpark in San Jose, then the A's themselves wouldn't be financially viable. It's a no-win situation.