I moved out to Australia last year, and my sister has been in Canada for a few months. I don't think either of us was entirely sure if we'd stick it out long term, but the Brexit vote has made the UK a lot less appealing.
The trouble is no-one is sure what's been voted for. Will it be a complete withdrawal from Europe, membership of the EEA, or will the UK remain a member of a reformed EU? All three strike me as possible outcomes.
@rocket mentioned a collapsing real estate market. This might be one of the bright spots of Brexit, as there's a generation who have been priced out of property, particularly in London and the Southeast.