A lot of what I do would not be a mystery to my great grandparents: wood heat, gardens, and water from a hand dug well. Other things are firmly in the 21st century: solar electricity, computers, and mp3 players.
In spite of doing a lot of stuff in an old fashioned way, I really don't want to live in the 19th century. I don't want a horse, or cows, or have to do every darn thing by hand. I like being able to drive places, have light at the flick of a switch, and be able to connect to the world with a computer.
Lots of things that were done back then were pretty darn hard. Plowing fields while looking at the south end of a north bound mule is not my idea of a good time. I'm more the read a good book in a hammock sort of guy. Instead of row crops, something like permaculture is more my speed. Set up a food system that pretty much runs itself. I've taken some steps in that direction and plan to do more.
As our energy resources start heading down to the 19th century level, it doesn't mean we have to live the way they did back then. We have many years of accumulated knowledge. There are plenty of useful ideas that don't rely on petroleum products. All that hippie tech from the 70's: alternative energy, unusual building methods, organic gardening for example, have had the kinks worked out of them. Decades later, we know what gives the most benefit for the least input.
Oil isn't going to go away tomorrow. However, odds are they'll be a lot less of it. What we should do is save it for things we have no substitute for and stop using it for non essential reasons. For example, oil derived medicines and equipment are essential for modern medicine. Should we be waisting precious oil on brightly colored junk toys that break the first time kids use them?
Some people in the sustainability movement envision a world where people live more like the Amish but also have computers. That's fine, but I think the Amish use too much energy and work too hard. My gut feeling is that techniques that work for a lazy guy like me should work for many other people.