Thus, I can't see it becoming a major campaign issue because when Democrats run on gun control, they lose. It's no accident they've all but avoided the issue the last couple/three cycles.

If the court in a 5-4 upholds the DC gun ban, it will energize the right. It will likely solidifies the mountain west, south (e.g. Virginia) and some of the Midwest (e.g. Missouri) for the GOP.

If the court in a 5-4 strikes down the DC gun ban, it will energize the left, but I don't think to the same amount.

For both sides, it will emphasize that the next president is likely to appoint one or two supreme court justices. Since the replacements are most likely on the left (Stevens, Ginsberg, Breyer, Souter) or in the middle (Kennedy), the impact is likely to be felt on the left not getting the court to impose what they can't achieve by legislative means.

Note, BTW, that the first sentence of the quoted article is erronerous: The question is most emphatically not "whether the Second Amendment protects an individual’s right to carry a gun" but, rather whether it protects the right to own one and keep it in finctional condition in one's own home. Determining how that might have ended up misstated by ABC is left as an exercise for the reader.

Once that's eliminated, the question becomes whether the Court has to reach any far-flung conclusion about the nature of the Amendment, or else can just hold that, WHATEVER it means, it doesn't mean that D.C. can't let you have rifles and shotguns but ban handguns.