Ars Technica has a decent rebuttal to the panic (icluding mine) over Indium and Gallium scarcity. That said, I think the recent trend in oil prices has shown how quickly scarcity can set in, and how ill-equipped the market is to actually predict real scarcity.
There's also the point that needs to be brought up: talking about the planetary "resources" of elements or compounds is worse than useless, because what matters in the end is (in the case of oil, and other mined commodities) proven or at the very least explored reserves. These are two distinct concepts in geology, and not keeping them straight can lead you astray.
To simplify grossly, a "resource" is basically an estimate of the amount of a mineral (for our purposes, this includes fossil fuels) in the ground and maybe it's purity. A "reserve" is something much closer to economic reality, with economic extraction a possibility and plans to do so. These aren't just scientific calculations: banks and financial markets will lend you money based on proven reserves if you'd like money to start a mining operation. Come to the teller's desk with a "resource" estimate, without some clue as to how to turn minerals in the ground in to economically useful products, and you might as well just walk away.
There's an important corollary to all this: a great deal of the stuff in the Earth is never going to be "reserves", because it is either too deep, too diffuse, or to tightly bound to other elements to be worth the effort.
It's widely accepted among the sane that humans are literally going to have to start eating "lower on the food chain": we have to start eating more plants, less animals, because animal protein is a very inefficient form of energy use. What's not often realized is that human industry is also going to have to eat lower on the food chain, in the sense that resources that require huge amounts of energy to produce and refine are going to be less affordable than simpler, low-energy materials.
Now, of course there's caveats to all this. If cheap fusion and nanotechnology proliferate, than maybe aluminum and titanium will totally displace steel and copper. (I am still, despite my pessimism, a sci-fi nerd.) But barring something huge, it's unlikely that we'll be able to replace our consumption of things like copper with more energy-intense metals like aluminum.