It is true that when a resource is difficult to use and produces little, its not in great demand. And when more efficient and productive ways to use it are found, the resource is more widely used.
But this doesn't mean that it will not become more expensive as it gets used up and more careful use of it will be made. Human nature will continue to function.
It's an unproven proposition, and usually only applied to industry. If my refrigerator is more efficient, I won't buy a second one. A more efficient car might give me an incentive to drive more, but that seems really marginal.
People who hadn't brought refrigerators before, might be a first one, though. And if there are extremely efficient, we might even switch to living inside refrigerators [1] in summer.
But this doesn't mean that it will not become more expensive as it gets used up and more careful use of it will be made. Human nature will continue to function.