Where do we want to be 100 years from now? You may ask, "Why do we care?" After all, we have serious problems now, and we need to deal with them right now. Forget this distant future stuff.
We care because currently, we lack a clear end-goal. For global warming, fossil fuels, and transportation, there's no obvious finish line anywhere in the near or distant future. When will we declare these problems solved? All we have is the ubiquitous Reduce-The-Bad mentality: "minimize the impact..." "reduce the consumption..." These are not clear end-goals.
Where do we need to be in 100 years? Take transportation: our cars and the fuel they run. The fuel needs to be made responsibly, using 100% renewable resources that don't add net-CO2 to the air. The fuel needs to be transported using 100% renewable resources, and produced using energy that is 100% renewable.
But it's much more than fuel. Take apart the car: the metal, paint, plastic, rubber, and fluids should all be easily produced and easily disposed of. They should fall into one of 2 "Cradle-to-Cradle" categories: 1) infinitely recycleable (like high-grade metals) or 2) truly biodegradable (meaning breaks down and nourishes the natural environment). There's no such thing as "acceptable pollution" or a law that says "you can pollute the earth this much."
Today, even our most sustainable cars like the Toyota Prius fall far short of these goals. The Prius runs on gasoline, a finite and CO2-emitting fuel. The plastic dashboard is made from petroleum-based plastic. The paints are not low-VOC or natural or non-toxic. The batteries are a mess from start to finish.
While it's true that progress is slow, that a silver bullet doesn't appear instantly, having these clear goals in mind helps drive our designs-pun intended. We don't need a scientific breakthrough like cold fusion to solve our problems. We can build cars now, today, using existing technology that meet all of the above criteria. If we could close our eyes and imagine driving a fun car made from recycled steel, non-toxic interior parts, recycled rubber tires, running on a clean local fuel, then maybe we would see that car when we open our eyes.