+1 to what JohnM said. Tesla (price drops) and the Chinese have shaken up the European market and prices can only get lower and lower.
I think the battery tech is pretty mature and sorted but it's the software inside the car that needs catching up. So the longer you can wait, the better the EV you'll get. Of course, that 20k might not be there in 2 years and that's the conundrum! But you might not need it as there should be second-hand 5yr-old EV's (taxi and non-taxi's) for sale.