It looks like my prediction came to pass. The Supreme Court did in fact strike down DC's handgun ban as in violation of the Second Amendment. It was much closer than I had hoped it would be. I haven't had time to fully digest the opinion, so I'll have more later, but you can read it here.
For those of you who care about this issue, be careful for whom you vote or whether you decide not to vote. The individual right to Keep and Bear Arms survived in the Supreme Court by a single vote. One change in justice could reverse this decision.