Brexit and Beyond: Why Americans Should Support British Exit From the European Union, and What Could Come Next, by James C. Bennett (warming: longish pdf). The cultural fit of Britain with Europe is not strong:
Continental Europe differs from Britain in a number of key ways. Britain sells a much higher percentage of its production to the world outside the EU than do its Continental members. It has a growing population, while the rest of Europe is shrinking, only a little behind Japan on the demographic crisis curve. Britain has a history and tradition of economic openness and flexibility, ranking in the top ten nations worldwide on the Economic Freedom Index, unlike the USA. The Continental economies have a strong history of centralization and detailed regulation of all aspects of life and economy, which is constantly demonstrated in EU regulation.
An intriguing option for Britain emerges, a sort of Sherlock Holmes option — once the impossible has been eliminated, whatever is left, however improbable, must be considered.
This option has been called the Commonwealth Union, the Realm Union, or the CANZUK Union, the latter name taken from the initials of its proposed core members, Canada, Australia, New Zealand, and the UK. It has a number of possible configurations, but is, at heart, a confederation of these four Westminster parliamentary democracies, although likely including other states such as Singapore.
A movement has recently sprung up to promote the idea of freedom of movement among the four nations, a proposal that has been strongly supported in polling in all of them. Once Brexit converts Britain’s current membership in the European Union into a looser free-trade relationship, it could easily participate in a Commonwealth Union. Similarly, such a Union would be compatible with continued free trade and cooperation between the USA and Canada.
A forthcoming book, A Most Audacious Union, will explain this in detail. See the article for interesting arguments in favor of such a “loose confederation.”