At the risk of going out on a limb:
If you assume the Supreme Court holds that the Second Amendment creates an individual right, and further that it affirms the ruling below by the D.C. Cir., without remand, then I believe the Commonwealth will re-visit ch. 140.
Here's a question... what happens if the 2nd is incorporated (eg, as in the case of say, case law striking down a handgun ban in chicago) and MA does nothing? I'm guessing at that point we would need an MA "test case" or something to force the issue? The reason I mention this is I doubt this horrible shithole of state would ever acknowledge that their laws are unconstitutional.... without someone pushing the issue... The state is corrupt enough that courts here would more than likely rule in favor of the state, constitution set aside.
-Mike