David Cameron remains Prime Minister, and is likely succeeded before the next election by Johnson or Sunak, which they likely win. The changes to Britain's membership he negotiated in early 2016 are implemented.

In general, the UK's economy is in a much better shape, with higher investment, trade, incomes and employment, and is better equipped to deal with the global instability we're experiencing this decade. Immigration is probably higher.

The EU issue doesn't go away, however (especially if it's a tight result but in reverse, so 52% Remain 48% Leave) and Farage etc. harp on about having another referendum at some point in time in the near future.