It is most definitely the cheapest way to heat houses and run cars. At least on raw economic costs; some utilities inflate electrical costs relative to natural gas costs in a way that makes a heat pump more expensive than natural gas heating, but that's just a distortion of the underlying economic costs, and only for some people.

We don't yet have electrically driven steel or concrete production methods, but this is a great opportunity for startups and new technology.

Steel will be more straightforward to decarbonize, but even if decarbonized steel is 50% more expensive, it will have negligible impact on the cost of downstream projects. And the industry can then apply their profit margins to a higher base cost. It's likely that either electrolyzed hydrogen, or with more direct electrical application with new methods that are more like aluminum refinement.

For concrete, it will be far more difficult, as a base chemical reaction to produce concrete releases carbon. However, there's significant room for improvement and new chemistries other than Portland cement, but worst case we will need to do carbon capture and sequestration. This will be more expensive, but it remains to be seen by what factor.

In any case, the extra expense of these most difficult to decarbonize areas will be offset by new opportunities from abundant, cheaper electricity.