Can aluminum take up the slack? I know long distance power cables are often aluminum. Even some of the larger gauge in-home wires. If copper prices rise too much, some demand will switch over to other conductors.
Sure, depending on the application you can just redesign to larger gauge aluminium. Aluminium has useful mechanical properties that trump the lower conductivity (such as power lines,where thermal cycles can make copper brittle). You could argue that there is a silver shortage in a similar way as the article has argued a copper shortage...
The lower conductivity of Al isn't important: you just use larger wires to make up for it and get the same resistivity. Al is so cheap that it's still much cheaper than Cu even with thicker wires. Al also has low density, so even with thicker wires, it isn't as heavy as Cu, which is important with power lines.