That's especially true in places with limited hydroelectric capacity.
Generally in places with aggressive renewable energy policies the price of electricity skyrockets and this benefits the fossil fuel companies too.
The places where wind energy has been most "successful," Denmark for example, tend to have some of the most expensive electricity in the developed world. Electricity in Denmark would be even more expensive than it is now if they couldn't dump their surplusses into the fossil fueled German electric grid whenever their wind turbines were producing excess power, or they couldn't import hydro and nuclear energy when the wind isn't blowing sufficiently. Wind energy also benefits Denmark by allowing them to export natural gas that they'd otherwise burn domestically for electricity production.
In the case of the "Grain Belt Express" it would be financially unsound to use these lines only when there was a surplus of wind or solar energy needing transport. In practice they will be used to move lower cost electricity from all sources to places where it can be sold most profitably. Calling this energy "green" is mostly an accounting trick.
Multi-billion dollar investments in wind, solar, and transmission infrastructure in this region will at best reduce the carbon intensity to a lighter shade of brown, as depicted on electricity maps in my previous post, and only double the price of electricity at the consumer's meter.
Ultimately wind and solar energy are no threat to the fossil fuel industry as they will only prolong our dependency on fossil fuels.