This previous answer is not correct from an economic point of view. For example, in economic terms, demand can never determine supply. Supply is defined as the amount of some product that suppliers are willing and able to supply at a given price. It has nothing to do with demand. Therefore, the first part of the previous answer is simply incorrect from an economic point of view.
Economics tells us that there can be three types of factors that can impact supply. These are changes in the price of inputs, changes in technology, and changes in expectations. Technology is not likely to change in a way that will make Blu-ray less efficient to produce, so that is out. However, the price of inputs could easily go up. As more and more electronic devices come to be on the market, the prices of various inputs for those devices may well go up. This would reduce the supply of Blu-ray.
Of the factors that can impact supply, the one most likely to reduce supply dramatically is the price of inputs.