According to the language above, the USSC broadened the case from specifically handguns to other types as well. I wouldn't read a lot into the specific type of firearm, unless you're talking full auto etc. But I'll bet the USSC gives the folks in DC the right to keep handguns, rifles and shotties as long as they don't violate NFA or GCA limits. THOSE we'll have to address in the near future, methinks. However, it is just as likely that the high court might give us the whole ball of wax, too. But at the minimum, my money is on a decisive and definitive ruling on Heller that will apply across the board and will have inclusion as a by-product.
There's just no way that the Court is going to mention existing federal legislation. Such legislation is subject to change at the whim of Congress and mentioning it would be make no sense to future Courts that would be charged with judging cases based on the protection of the Second Amendment.
If the Second Amendment doesn't protect machine guns, that lack of protection is completely independent of any acts of Congress. Similarly, if the Second Amendment does protect machine guns, then an act of Congress saying otherwise is irrelevant.
The Court must decide that the right to keep and bear arms is an indivdidual right.
The Court must decide that the right encompasses self-defense as well as preparation for militia service.
The Court must decide what level of scrutiny is to be applied, UNLESS they can rule that any level of scrutiny would forbid the banning of a useful category of arms. But that would immediately suggest that machine guns cannot be banned categorically.
All of this has tremendous immediate relevance to statutes throughout the country. The Ninth Circus has a bucket full of cases which have been decided based on the "collective rights" nonsense, denying standing to people whose rights have been infringed. They are going to lose their favorite method for denying the right to keep and bear arms. They will no doubt come up with something else, but, hopefully, the Supreme Court will stop denying cert for such cases.