Not all will leave but some will.
We could stop the PG situation by saying a spouse who doesn't work in a business cannot own shares in the business of a spouse but that would be very unfair as they would then be treated worse than people who are unrelated and who own shares in businesses in which they do not work.
We could say anyone who works in the UK even for one day a year is taxed here whatever their status, residence, domicile, on all their worldwide income even if it is already subject to tax in another country but that kind of double taxation is very unfair.
None of those things are very palatable. There are very very few rich people and many of them generate more corporation tax through their businesses and work for British workers than any tax they might save by being taxed on their income only abroad and indeed some move here or used to for our lower tax than in say Scandinavia.
This is simply an issue of fairness and the poor being jealous of the rich. It is not about large revenue that would generated for the nation. Indeed the higher the tax rates the less money you get in to pay out to the poor. Tax the rich less and the poor will have mroe money in their benefits but may be more unhappy because people (being rather silly) are happier with less if others have less. The green sin of envy etc.