Its unlikely that it will run out of coal for the fire. There are several places in the US that have similar coal mine fires. They burn for hundreds of years. I guess there is no way to really put the fires out.

In Pennsylvania there are several mine fires in different places. Last year when we went to visit my brother in PA we got lost and ended up driving in Centralia, PA. There were all kinds of detours and roadwork. They have a burning mine. It is a creepy, creepy place with a bad vibe. I could feel it just driving around there.

https://en.wikipedia.org/wiki/Centralia,_Pennsylvania

Supposedly Centralia, PA was the inspiration for the movie "Silent Hill". I don't know if you ever saw it but it captures the dreary feeling of the place.

I never realized there were mines that burned for so long. The good thing in NSW is it looks like its in an uninhabited area.