There are a number of studies that indicate that coal production may peak in about 15 years. Chris Vernon has summarized some of them in this post.

Heading Out has argued that these studies may forecast a quicker end to coal than will really be the case. He believes that the decline in production in many cases occurred because cheaper (and/or better) alternatives became available. The forecasting method misses the fact that if the alternatives are no longer available, people may go back to these sources, and they will again become economic.

Coal prices are very much higher now than they were in the recent past. At one time China was an exporter; now it is an importer. There are many other countries that would like to increase the amount of coal they burn, since oil is very expensive. Prices have risen because demand is much greater than supply. This is one story talking about the higher prices.

We use a great deal more oil than coal. When there is a shortage of oil, there is pressure to ramp up coal to compensate. In practice, it doesn't really work, though. It is almost impossible to increase the amount of coal available for export very quickly. One needs to be able to extract more coal from the ground; then one needs railroad cars, barges, and ships to transport the coal on. Some exporters have recently had difficulty for a variety of reasons. South Africa has recently reduced its coal exports because it needs more internally.