My bet is that after Brexit the EU will use psychological rather than economic tactics against UK. E.g. target football transfers as this has big impact in minds of voters but low impact on EU economies.
So free trade of cars but 200% tax on euro footballers?!
As no one including politicians, academics, industrialists, bankers or the clergy have any idea what format Brexit will take, whether it will occur, or when, how on earth can any of us speculate as to what effect "it" might have?