This is not even the interesting thing about lower battery prices. It may happen, but the interesting thing is that it enables different kinds of electric vehicles.

If the cost of the battery in itself rivals the entire price of a subcompact economy car, you obviously can't put one in a subcompact economy car and offer a competitive price in that market. So right now the electric vehicles with significant range are premium products. With cheaper batteries you could have a traditional subcompact economy car with mechanical controls etc. and an electric powertrain.

Likewise, trucks need large batteries to have adequate range while hauling loads. So this gets you to an electric version of the Ford Maverick, for example.

It doesn't just lower the price of the existing models, it allows the low-end models to exist.