As a citizen of Germany I would like the brexit as a wake up call to the powers of the EU and my government alike.
Reading papers and watching the news I see that happening already. They talk a lot about "less bureaucracy" and "more power to the regions". My fear is that if the Brexit will not happen, all this will soon be forgotten again.
British business aviation itself will not suffer from a Brexit I guess. On the contrary, they might be able to rid themselves of the cheap competition from the continent that takes a lot of their business away right now.
But what is certainly going to suffer are the other businesses around aviation in the UK. For aircraft maintenance and repainting, UK companies have an excellent reputation and quite a few of the aircraft in our company go there for these tasks, even if UK prices have always been a bit on the expensive side. But after a possible Brexit this will probably be over. The same with our simulator visits to FSI and CAE in the UK. It is already more expensive to go there than to the States, but at least it saves us traveling days and TSA bull****. But if UK prices go up after the Brexit we will go to the States again. And most of the companies on the Continent as well I guess.
For us business aviators on the Continent, a Brexit might even bring about more business. Instead of contracting companies in the UK (we fly a lot for the automotive industry) our customers might move south-eastwards to Romania, Czech, Slovakia, whatever instead. Which means more flying hours sold and better hotels and food for us crews for 1/3 of the price...