Overnight capital costs are significantly lower for new gas plants than new coal plants. Real capital costs are lower yet since gas plants are faster to complete. Fixed O&M costs are also lower for gas. The shale revolution made fuel for them cheap too. There's no combination of circumstances that presently makes a new coal plant cost-competitive with a new gas plant in the continental US.

See table 1 here:

https://www.eia.gov/analysis/studies/powerplants/capitalcost...

The renewable costs are already badly outdated but AFAICT the relative prices of coal and gas plants are still about right.