A similar suit was brought against Nike when they claimed Tiger was using a golf ball that they sold but he was really using a ball that couldn't be purchased. The plaintiffs won that case and Nike eventually released the special Tiger-only ball for public consumption.
People have wondered when this would happen in tennis for a while. Frankly, with the Nike-Tiger case on the books the racquet companies have been walking on thin ice with their paintjob shenanigans and they know it. It will be interesting to see if this case goes anywhere. The key will be proving that Federer currently uses an older model under a new paintjob. They must have some evidence of this otherwise I don't think they would take it to court. It would be cool if they bring sawed open racquets and stuff into the court room.
A possible outcome of this could be that Wilson will start selling Federer's actual racquet again. (Again, because many people feel that the K90 was, in fact, the frame that he really uses. When they brought out the K version they were responding to some public outcry that players couldn't buy Fed's real racquet. So they said, well, here you go. Then, with the BLX, they changed the layup completely - removing kevlar and adding basalt.)