When the Second Amendment says quite clearly that a right "of the people"..."shall not be infringed" that would sort of lead one to believe that the area is not open to negotiation.
Here's part of the opinion released this morning:
"Given the empirical and local value-laden nature of the questions that lie at the heart of the issue, why, in a nation whose constitution foresees democratic decision-making, is it so fundamental a matter as to require taking that power from the people?" Breyer wrote. "What is it here that the people did not know? What is it that a judge knows better?"
There's a catch though. Breyer is writing in dissent! The power that he refers to as being taken from the people isn't the power to defend themselves and their property from goblins and oppressive governments. He's good to go on that. It is the power of the select few to determine what they want to take from you that he seeks to defend. He's squarely for the power of the government of Chicago to deny you the right to protect yourself and render your family helpless in a city riddled with criminals and thugs.
Here's more on the story of the day's Supreme Court rulings:
McDonald v Chicago Headlines a Good Day in Court
The actions of the day also included a slap-down of a government oversight board as well. That one, however, won't have permanent impact particularly in view of the current administration's agenda.