To mirror your point - sunlight is a finite quantity. Eventually our sun will die and then there'll be no more sunlight. I'm not really seeing the reason to invoke this line of reasoning because it doesn't scale well to human civilization timeframes. Secondly, where there is a need there is usually a way - if we really, really, truly want more coal and oil, damn the cost, we'll never run out, ever - the hydrocarbons embedded in the Near Earth Asteroids could keep us going for millions of years. Far fetched sure, but it illustrates the point that resources are available to use if cost considerations are immaterial.
A less far-fetched alternative are the
coal fields off of Norway's coast:
They calculated that there are 3000 billion tons of coal off the Norwegian coast. Most of the reserves are located at Haltenbanken. This compares to today's proven and recoverable world reserves of 900 billion tons of coal.
That's just ONE localized coal field which is presently uneconomic to mine and that ONE field has 3x+ the coal of ALL of the world's economically viable recoverable coal.
As I said, we'll never run out of coal and oil because at some point their scarcity will push up the cost and they won't be worth the effort of getting out of the ground in that their energy content could be replicated through other fuels/processes. If no viable alternatives develop then our attention will turn to reserves which are presently economically nonviable and our energy costs will increase as a result.