We could take all suburban United States off of fossil fuel heating with solar heating. But that would require planning up front and cost some powerful people money, so we can't.
By heat I think the parent mostly means industrial process heat, which is mostly supplied by natural gas now. Coal is still used in metallurgy.
Electric heat is rare since it’s inefficient (thermodynamics) and thus expensive but it’s used in applications where you need precision temperature control.
Of course if solar and batteries got cheap enough you could just say F it and use electric resistance heat everywhere. Time your peak production to coincide with mid day when solar is at peak.
We could take all suburban United States off of fossil fuel heating with solar heating. But that would require planning up front and cost some powerful people money, so we can't.