I doubt if Brexit will have any real affect on the hobby. The initial decline of the Euro from the 130's to 108 is still beating up the European buyers. The new cold war with Russia seriously has reduced Russian Federation citizens buying. So a temporary swing of the pound should do little. Other than that, the US Post Office and the British Post office will continue to do business as will all the banks.

So Brits and all of us can continue to buy and sell.