American Needle doesn't actually score a victory here, at least, not yet. The case merely returns to district court, where it will be reconsidered under what's called the "Rule of Reason." A doctrine dating back to Standard Oil, it states that monopolies aren't inherently illegal, only if they "unreasonably" restrain trade. That's still up for debate with the NFL's licensing deals, and the Supreme Court gave no indication on that one way or another.
The NFLPA wins big. They had been terrified of a league with unchecked power to act unilaterally in labor issues, especially with an expiring CBA. Not that the player's union is particularly powerful as is, but at least the league won't be able to dictate salaries, free agency conditions and age restrictions without getting into the CBA first. If the NFL had won this case, those would all have been very real possibilities.
The NFL doesn't so much lose as they fail to win. The league had been hoping for that antitrust exemption, which would have been a hammer to bring down in myriad smaller cases against the league. It would have given them sweeping powers enjoyed by no other business other than Major League Baseball. Now, those other cases proceed on their own merits.
Other sports leagues are not happy right now. Both the NBA and NHL filed amicus briefs in support of the NFL, hoping the precedent would give them more powers. With the NHL recently having to bail out a handful of teams, and a labor stoppage looming for the NBA, it could have been big. NASCAR, MLS, and most chillingly, the NCAA also publicly supported the NFL.
Baseball, on the other hand, still enjoys the country's only antitrust exemption, dating back to a 1922 ruling that's considered curious today. There's no indication the High Court would revisit that ruling, but should it be challenged there's certainly a precedent for it now. A limited one, however; American Needle v. NFL appears to apply specifically to merchandising.My personal opinion is that none of the major sports groups in America deserves an anti-trust exemption. The rightwing nutters should support my opinion as well because they supposidly worship free trade. Protecting large groups by giving them anti-trust exemptions goes against everything the nutters believe in.