Be careful what you wish for. We know how four people per "side" are going to feel about this, but who knows about the swing vote? He (Kennedy) may have had a negative experience with privately held firearms. I note that he had some connection with the California National Guard (which, again, could be a good or a bad thing), but in the world of precedence, you usually only get one bite at the apple. I hope Kennedy's alleged conservative and libertarian impulses come to the fore, and that he takes the time to read and consider what the Founders said about their Amendment. Of course, whatever is decided cannot erase the fact that Mr. Madison, et al, regarded keeping and bearing arms as an inalienable right.
Not so fast. The usually dependably statist Ginsburg has already voted for the individual RKBA, IIRC, and Scalia sometimes votes "conservative" as opposed to "Constitutional", in favor of the government over their masters.