Cheaper power would just lead to greater consumption of power. If cheaper solar and wind power replaces fossil fuels in some areas, the fossil fuels will just get used in others instead. Such as bigger vehicles and more long-distance tourism.
Edit: perhaps coal would be phased out, without government intervention to save it. I don't think oil production would go down on its own.
Edit: perhaps coal would be phased out, without government intervention to save it. I don't think oil production would go down on its own.