If your wife already figures you have enough guns, ask her if she has enough shoes. Last time I checked my closet, there were more of my wife's shoes in there than my guns.
About the only space I see in there -- unless you are planning to go to Africa where some of the countries require a minimum bore of .400" -- is between the 223 and the 270. You could go for a 240 Weatherby, .243 Winchester, 6 mm Remington, .257 Roberts, .25-06. If I were you, I would go with either the 6 mm Remington or the .25-06. The .25-06 is a great deer and antelope cartridge. The 6 mm Remington is a great antelope and deer cartridge, but may be arguably slightly light for mule deer at long range? You may have to reload your 6 mm cartridges, as I would guess this ammo is not commonly available based on the fact that few if any rifles are currently manufactured in this cartridge. I might go for the 6 mm Remington in a 26" medium weight barrel. You can use the .270 for deer hunting and the 6 mm for Pronghorn hunting. Of course, your .30-06 can be used for most everything you can hunt in the lower 48. If you want to hunt grizzlies or brown bear, your .338 Winchester magnum has you covered. Thus, all those other rifles can only be justified as special purpose, niche rifles. Hence, the idea of a pronghorn niche rifle does not seem out of place.
