My ideas of a "functional" gun battery were originally influenced by the writings of Mel Tappan and other early "survivalist" authors.
The essentials are pretty much the same as most of us have mentioned. Some don't need some of the guns needed in more rural areas. But your list is very similar to what I have listed only I went a different direction on some things. I have the .22 and a shotgun and the semi-auto centerfire (but mine is a SKS instead of a .223 which mean an AR of course or something similar anyway), I have a 30.06 instead of a .308 and I have a .45 for HD but I did switch to a .40 because of it's ability to penetrate steel in car doors etc.. Things like gun needs never really change. I have added backups to my collection and I've made a difference between a .308 for larger game and a bolt action .223 for smaller game and varmints. But my list would match up with this list especially when I first got started with my list.