Eugenge Volokh asks the question. I figured I’d offer an answer. I already commented roughly the same thing over there.
I suspect an individual rights ruling would give the Democrats some cover to retreat farther from gun control in the 2008 elections. The Democrats aren’t going to want to get backed up against the Bill of Rights on the issue. The die hards in the party will switch their rhetoric to “It’s an individual right, but…”, but more moderate democrats will have some extra political cover from the courts.
A ruling along liberal/conservative lines, with Kennedy joining the liberals I think will most definitely fire up the gun vote quite a bit. But I think the same result will happen even if the the split isn’t as much along ideological lines. I would expect the issue of Supreme Court nominees to be the real issue, rather than specific gun control proposals. The main thing gun owners will want to see is that the candidate will nominate justices that will overturn the Parker decision.
I think where the ideological correlation of the vote will end up coming into play is in what party gains the most from it. If it’s along ideological lines, that will probably tend to play into the hands of the Republicans. If it’s not, either party could gain.
I should also note that I think a defeat at the Supreme Court, over the long run, is a disaster for us, because of the difficulty, even if you can alter the political climate for a very long time, in getting existing precedent overturned.  It’s not impossible, but it’s an uphill battle. Over the long run, the idea that the 2nd Amendment is meaningless will take hold, and we’ll be doomed. The gun controllers will have the political cover they need, and we’ll lose our greatest ally, which is the Bill of Rights itself.
I can hardly blame folks who believe Parker is too big of a gamble. This will either be our greatest victory, or our greatest defeat. Here’s hoping the former.
The civil rights movement didn’t die with Dred Scott or Plessy v. Ferguson.
The fight will continue, but it’ll be an ugly pitched battle. If we do lose at the SCOTUS level, you’ll see a rash of gun friendly states repealing gun laws left and right and reacting to it the same way they did the Kelo decision–with legislation to protect their citizens where the feds fail to.
So MD, NY, CA, and IL will use our defeat at the SCOTUS level to pass sweeping gun bans. Tons of other states will retaliate by telling the BATF to go fornicate themselves and retaliating by yanking gun control laws and passing amendments to their own constitutions protecting the RKBA (assuming they don’t already…what the gun banners seem to ignore is that 33 states recognize the RKBA in their own constitutions–so even if the anti-Parker forces win…they still lose.)