The gist of this is that now statement in and of themselves cannot be actionable until it can be proven that the mind of the person making the threat actually intends harm. The defendant in this case, Anthony Elonis, argued that he was a rapper and his statements could not be taken in context (i.e. "Fold up your PFA (protection order) and put it in your pocket Is it thick enough to stop a bullet?" and "I've got enough explosives to take care of the State Police and the Sheriff 's Department.")
Internet trolls rejoice. Now anything can be said, no limits to speech, no consequences as long as it can be proven that you don't mean harm. If in doubt, just sign all threats with JK (Just Kidding) or RL (Rap Lyric). People have been kicked off flights for jokes in poor taste (bombs, threatening airline employees...) but now the intent of the threat has to be proven. The internet has always had a large troll population. Now they can come out of the shadows, raise their middle finger, grin, and make very specific threats with impunity. If caught they can laugh and say JK/RL.
This leaves a most unclear situation where it becomes far more difficult to determine at what point does a statement become abuse and actionable? This is likely to spawn enough confusion about this ruling (7-2 no less) that more cases will be heard and with opposing rulings and head back to the USC for further clarification.