In 10 years when the batteries will cover 24 hours of demand to cover few weeks without sun and wind nuclear will be too expensive as reactors requires maintenance even when they do not work. Coal will be vastly cheaper beating even natural gas as one can store coal in bulk.

But right now we do not have excessive capacity and smoothing the curve for nuclear allows to burn less coal and natural gas. Essentially right now batteries are killing peaker natural gas plants, not nuclear or coal.