How would that be different from coal in the past?
There are too many suppliers of Natural Gas, it is a very competitive market, which is what has driven the price low with the new shale supplies.
Most all coal sales have been either long term - up to 30 years - or spot. In either case there's no room to raise prices capriciously because there is always a trainload or two ready to ship from the competition. Every mine is in a cutthroat race for market share.
As an aside, natural gas providers have a history of working together. Consider their shared use of pipelines. They also join hands to bankroll things like the 10 year program in Denver, sending armies of brain dead green weenies door to door gathering signatures to petition the local power plant to convert from that dirty, nasty, black coal to the clean, green natural gas.
If a power plant converts from coal to gas, it's a real task convert back. No 30 day coal pile, the conveyors have been dismantled, equipment sold, and the handlers are down the road kicking cans. It's so much easier to use the pipeline and accept the price increases. The PUC will approve the rate hikes anyway.