no its not - four justices (Alito, Roberts, Scalia, and THomas) will likely find that the D.C. reg violates the 2nd amendment. Four justices (Ginsberg, Beyer, Souter, and stevens) will likely find that the regulation was a reasonably necessary restriction within the city's powers that serves an important interest.
That leaves Kennedy as a "swing vote" and nobody knows where he sits on this issue.