I know how to milk a goat! heh... I know how to make a thread from wool, as my grandparents kept mountain goats, and my grandmother taught me how to spin the thread with a simple spindle my grandfather made.
I don't think this is lost:
If necessity called for it, I doubt that any willing adult couldn't figure out how to work a needle and a thread! So simple mending seems too... well.. simple! So I don't think that's truly lost. Of course a few mistakes can be expected, but a needle pulling thread to connect fabric is simple enough concept that I'm convinced people can do if they have to.
Making clothes from scratch is certainly a skill, but I bet not everyone was able to make gorgeous dresses and well-fit clothes in the past either. Some people were better than others, and I'm sure it's the same way these days, some will be more able to pick up this skill than others.
I also don't think that cooking without frozen packages is out of question. The idea that you can use fire to cook is pretty simple. Make fire - fry things! That's not that hard, and even kids can make "fire - food" connection. We are not talking gourmet meals, right? We are talking about survival, so I'm sure people can figure it out. As far as ketchup goes - I grew up without it, so to me it's just a recipe that you either know - or you don't. I'm sure people in the past didn't know every single recipe, so I'm not sure the ketchup argument holds for "skills from 100 years ago". I'm sure we can find recipes that are lost skills, but I think cooking is kind of like language - always changing, and we wouldn't consider talking as a lost skill just because we use different words these days, kwim?
As far as baking bread goes... once again... I think "flour, water, yeast" = bread is not that tough. It won't be tasty (I can't make bread you'd want to eat

) but it will be bread, kwim?
What is lost:
Now, hunting, tracking, knowing plants is a whole other story. You can't just pick it up through trial and error, someone has to take you out and teach you what plants are edible and which ones are not. Knowing herbs and how they can be used to heal is a craft I wish I had! I think while some people certainly knew more about it than others, it seems to me that an average person was very well versed in basics. My grandmother wasn't a healer, but just from her childhood she knew certain plants and their uses, and it seemed to have been part of general knowledge. (makes me want to go out and find a good book on herbs... )
P.S. I am putting the recommended book on my wish list. Thanks for the recommendation!

P.P.S. I really like the D&D reference AND the perfecting what you are good at recommendation!
