Which is nothing more than a pool of people that the Organized Militia draws its members from and has no rights, duties or responsibilities. The Unorganized Militia (from the Militia Act of 1903) is NOT the Well-Regulated Militia defined in the 2A
I submit that while the unorganised militia is "nothing more than a pool", the individuals making up that pool do have rights, and while the duties and responsibilities are seldom taken up by individuals in this day and age, they still do exist.
The Second Amendment does not define a well regulated militia (or any other kind), it simply states that the existance of one is necessary for the security of a free state, and that is why government should not infringe on the right (of the individual, or the state) to keep and bear arms.
The unorganised militia does still exist, and even though not utilised in the manner envisioned by the Founders, it is still there.
As to the argument that private citizens with their own arms could never defeat a military armed with tanks, jets, artillery, bombers, etc, it seems valid on the surface, but when thinking about this nation, I think one needs to look deeper. The difficulty and expense our military has had overseas, facing a tiny fraction of the population, in nations without a cultural history of individual freedom, without a cultural history of legal private arms ownership, without many of the things common to our nation, has been enormous.
I think that kind of situation, in this nation, should it ever come to pass, would face the military with even larger problems, including a significant segment of the population at least tacitly supporting "insurgents", and including friends, sons and daughters of "insurgents/rebels" inside the military and in government, which would make it even more difficult for a military victory. Certainly our militia would not be likely to defeat our regular military on the field of open battle, but not all wars are won on the battlefield.
As said many times before, the mere fact that we, as individual citizens retain our right to arms, and the (at least theoretical) ability to resist a tyrannical government means that we will never need to actually to do so.
Future generations may not see things this way, and great "change" might well occur. But for now, thats the way I see it.