I have thought about this topic as well. There are so many skills that could come in handy should the SHTF. The ones you have mentioned of course but also consider things like; mechanics to keep cars/generators running, ropecraft for climbing/rappelling, horsemanship, electronics (fix that radio), etc. I know that there is only so much that one person can learn and basic survival skills should be at the top, but the fact of the matter is that we all depend on other people to truly "survive" over the long haul and our individual skills and expertise can all become very important. Learn something new as often as you can.