Despite headwinds, natural gas reliance set to grow in much of US

In the short to intermediate term, Holland says there could even be an increased reliance on gas-fired generation as coal and nuclear power plants continue to retire. But as more renewable and distributed generation enter the market, there is a good chance the role of gas could shift from baseload to quasi-baseload.

"There is at least one scenario in which the last combined-cycle gas turbine could be built in the next seven to 10 years," Holland said, especially if energy efficiency and demand response continue to erode demand and renewable generation continues to grow.

"You are already seeing that in the West. You can't build a combined-cycle plant in California, and that trend could roll out for the rest of the country."