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.
This is an interesting question. No one can predict this with any precision. No one has a crystal ball.
With that said, I would say that as long as there is demand, companies will produce blu-rays. Profits speaks louder than almost anything. As far as I can see there will be only two reasons why blu-rays are in short supply. First, if everyone wants blu-rays all of a sudden in a massive way in a short period of time, then there can be a shortage. I really do not see this thing happening. Second, if there is a natural disaster at a blu-ray plant, I can see there being a shortage, until they rebuild.
Apart from these two scenarios, I cannot see a shortage problem developing.