Second the world exists out of more goods than champagne, cheese and cars... . I see you make a big deal about German cars but in the whole scheme of things that is really small. And I dare to ask if a lot of British people will be still able to buy those cars to begin with, as I see how the pound is falling fast.
And third you are dealing with the EU that exists out more countries than Germany and France. Yes, because of their size they have a big position but please let stop that intellectual dishonest narrative that all other countries are living under some-kind of French-German dictatorship where they don't have any saying.
In order to not get job losses, both have to cooperate
Occasionally you see someone sitting around reading the newspaper and drinking coffee, ready to jump into action should something go wrong. The times where the industry consisted of huge factories filled with blue collar workers assembling cars by hand is long over.
The industry has two years to focus on other markets to export to. There might be some impact but it won't be catastrophic or lead to massive job loss.