Sorry to disappoint, but as I am not Boris Johnson's confidant I have very little idea how the disaster known as Brexit is going to pan out.
I will update this page as soon as there is any clarity.
However, one thing that Brexit has done, is to give other EU member states such as Spain and Portugal an opportunity to entice expats to take advantage of EU living by becoming tax citizens of their countries. They are offer general tax incentives which include exemptions in terms of car matriculation taxes if you have owned your car for a period of time.
I am not a tax expert but I know people that are, if this is of interest, please call or email me.