Grandad1943: It may be that motor manufacturers will build electric cars outside Britain after Brexit although this may depend on any deal that is concluded between the UK and the EU. It may also depend, ultimately, on the size of the market for electric cars in the UK. As it is, projections suggest that, by 2021, China will dominate the production of electric cars, producing more than the US (the second largest), Germany, France and Japan combined.
I agree with you that it is difficult to predict the political landscape. We've had several examples over the past few years when the experts have got it wrong, even when predicting an event very near at hand. I do not agree that it is clear that we will see massive changes in infrastructure, social fabric and economic outlook because of Brexit. Having had some experience of forecasting, I do not believe it is possible to predict the future accurately, whether we are in or out of the EU. Projections are too regularly wrong to be given a high degree of confidence. What is clear that we are undergoing fundamental change because of, to name but three factors, the internet, recognition of climate change and rapid world population growth over the past 100 years. As regards Brexit, the forecasts of collapse if we even voted to leave have so far proved groundless. I suspect we will muddle through but like everyone else, I cannot be sure.