Although Anthony Kennedy joined all three decisions in which the Supreme Court has upheld the constitutional right to keep and bear arms, his retirement probably means the Court will be less reluctant to define the contours of that right. In the decade since the Court first ruled that a law was inconsistent with the Second Amendment, it has passed up almost every opportunity to resolve lingering questions about which forms of gun control are constitutional. It seems clear that Kennedy bears much of the responsibility for that reticence.
It takes four votes to grant Supreme Court review. Two justices, Clarence Thomas and Neil Gorsuch, are on record as criticizing the Court's neglect of the Second Amendment. On three occasions, Thomas has written dissents arguing that the Court should have agreed to hear a challenge to a gun control law. Last year, in a case involving California's prohibitive restrictions on carrying guns in public, Gorsuch added his name to one those dissents.
While Samuel Alito did not join any of those dissents, he seems to favor a more aggressive defense of the right to arms recognized in District of Columbia v. Heller, the landmark 2008 decision that overturned a handgun ban in the nation's capital.