You actually can’t ‘just all retool the factories’. The mining of certain materials, notably copper, becomes a limiting factor. To produce the worlds 100,000,000 motor vehicles per annum (given a generous assumption of 50kg of copper per electric vehicle) would require 5 million additional tons per year, a 20-25% increase over current figures. Meanwhile the cost of refining increases exponentially with decreasing ore grade.

Sure not every manufacturer would go out of buisness, but the industry would absolutely collapse.