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.
You may be right, but if the individuals you named rule as you suggest: 1 Leftist for RKBA, and one nominal conservative against RKBA, that still equals 4-4, with Kennedy as the swing vote. I would rather not have to fret about it.