So I have a new chap starting in September. He asked whether he needs a visa, I said no, existing rules will apply when he starts and although sadly it now looks inevitable that we leave the EU at the end of October, we can assume things will continue as they are for a transition period of around a year, as it would be too complicated to do anything else.
Secretly I worry slightly that if he travels home at Christmas, as I'm sure he will, he might have some difficulty coming back to the UK if they ask him then decide au pair status isn't valid anymore or something.
Clearly, au pair travel status is, quite rightly, not going to be at the top of anyone's agenda for sorting things out when we go, so I do wonder if there will be a period when either no one knows, or the whole thing grinds to a halt because they decide no one can au pair until they know what they're going to agree about it.