The law is less precise than people make it out to be. There still hasn't been a defining legal case for fair use the way that there have been for other aspects of the law, and I doubt that this will be the one. The likely outcome is a sort of average of what both sides arguing: Google gets to keep doing what it's doing, Oracle gets more money than they deserve, nothing changes on the legal front.
The SCOTUS cases that happen happen out of desperation —the plaintiff or defendant has so much at stake that the options to turn back don't make any sense to them. Fair use invokers are generally businesses that can afford to pay to avoid a fight, and are used to grudgingly cutting checks, or individual citizens who, while concerned, understandably don't have the same dedication that they do when it comes to matters of security and human dignity. Maybe there will be an artist who wants to put on something that would be infringing but for a fair use exception and is wiling to fight to the bitter end for it, but that's the only way it will happen. Google and Oracle aren't really interested in fair use, they're just using the law the barter on the price Oracle can extract.