I think that for your run of the mill stuff that's readily available everywhere people will start to shop locally - i.e. UK buyers in the UK only.
High end, hard to come buy, gear will still be desirable wherever and those who really want it will need to pay the premium.
Expect new sales for Warwick/ Maru and the like to drop within the UK so those already here will become in demand.
European buyers for Status, Overwater, Wal and the like will also have to bite the bullet.