You see how the .30 Carbine cartridge is so maligned (e.g., Chosin Reservoir), yet it has greater energy than the .357 Magnum (The .30 has ~971 ft/lbs at the muzzle, while the .357 has ~650, both FMJ's).
We go with the 3.5" S&W stainless Model 6X .357, a Springfield stainless 1911 .45, and a Rem. 870/Wilson/Scattergun for peacetime home defense; but I roll with a Beretta 92FS, "old" mags, with Crimson Trace set at 7.5 yards, so I'm not advocating for the .30 Carbine.
I'm thinking about timing of any terrorist rampages, and I think that we won't have time to return to our homes or places of secretion and retreive our defensive tools.
Thus the terrorists will be faced with only the weapons which good Americans have "on hand," and they know it. Mostly just pistols, though many of us can handle a pistol. So it might be a good idea to have an inexpensive .30 Carbine in the trunk, with some appropriate magazines, in order to assist the LEO's if an attack takes place.
The .308 is still the "bee's knees" when it comes to a soft target long shot. I grew up using the .30-06, which comes a close second to the .308. A good .30-30 lever is probably the best all around rifle to have around in this part of the country for brush.
Personally, if I could ever afford it, the Springfield M1A would be one of my best friends.