Well, have no fear. The long-term supply of indium is both sustainable and reliable.
In fact, the abundance of indium in the earth is higher than silver, which is not considered in short supply. Additionally, indium containing mines have been discovered in numerous locations such as Portugal, Peru and China. Indium in the world today is plentiful and supply limitations should not become a problem.
Details on the world supply of indium and gallium were presented at the 22nd EU Solar Conference 2007 and the paper on this topic can be found here.