Urgelt:
As Ms. Lithwick pointed out, there is not much precedent about how to interpret the 2nd Amendment. Contrary to your assertion, the Court has never answered that question.
I think you are confusing the existence of a right with courts' decisions to apply, infringe, or ignore it.
Black people had an explicit consitutional right to vote in this country from 1865 to 1964. The fact that this right was ignored by courts and trampled on by state governments was an infringement of it, but that neither destroyed the de jure right nor rendered it any less valid. Nor was any "new right" created by the Civil Rights Act - the pre-existing right was recognized and enforced, the way Congress was supposed to have done a century earlier.
Urgelt:
That pesky phrase about a "well-regulated militia," at the very least, legitimizes the question, "just what is the fundamental right here for non-militia citizens?"
Since the militia is "the body of the people" and "consist[s] of now of the whole people, except a few public officers," I don't see how that question is relevant.
The more appropriate question would be whether exercise of the right is limited to weapons and practices that are of direct use in militia service, or to weapons and practices that are related in any way to militia service (as with Gura's argument that simply making the populace more generally familiar and proficient with firearms is so related), or whether the militia clause is an entirely distinct provision as Lithwick says Justice Kennedy indicated?