What? In the northern parts of of the US at least virtually nobody heats buildings with electric power. It’s gas or oil, which are not affected by the problems of maintaining capacity on the electric grid.
The road to zero carbon emissions passes through reducing carbon emissions by converting existing demand for electricity to renewables.
So saying 'well, lets solve the easy part of the problem with renewables but lets ignore are the hard problems' is not a acceptable.
If you want to actually propose a solution you need solve all these problems in the next 30 years.
If as you say electricity expansion is 'inconceivable' then we have already lost anyway. Because we will need more electricity for electric cars at least.
It only seems inconceivable because we consider it difficult to expand electricity generation without building coal or gas plants. Looking at historical examples you can see that you can have very rapid expansion with nuclear is not 'inconceivable at all'.
France is case and point, it already uses electric heating in many places. And they did this with 60s technologies in the 70 and 80. But somehow it is now impossible. How does that make any sense at all?