First among the open questions, and perhaps one of the most important of them, is whether this ruling applies beyond the federal government and the District of Columbia government (assuming that it is settled that those two entities at least are now covered).
It is absolutely clear that the Bill of Rights’ specific guarantees of individual rights do not apply to any level below the federal government – that is, to state, county and city governments — unless the Court has ruled explicitly that they are to apply at those levels by a process that is called “incorporation.” The Court has read into the Fourteenth Amendment — an amendment written to restrict state and local government powers — many of the rights in the first ten amendments. That process began in the late 19th Century, and continued up through the first three quarters of the 20th Century.
But the process has not meant a total absorption of the Bill of Rights in the Fourteenth Amendment. The Fifth Amendment right to be charged by a grand jury has not been applied to the states; neither has the Seventh Amendment right to a jury trial in a civil case. And neither has the Second Amendment.
But conservative jurists, like those who made the majority in the Heller case, usually are not fond of lifting parts of the Bill of Rights out for inclusion under the Fourteenth Amendment. Given the glowing rhetoric applied to the virtues of an individual right to have a gun, perhaps that reluctance might be overcome.
If, as expected, the NRA or some other litigant goes after a state or local gun law, relying on the Second Amendment, the Court may well have to answer explicitly whether it applies at all to such laws. Some already are reading the Heller decision to signal a willingness say “yes” to that question; the evidence of that is of an uncertain nature, though.