Does a new British Empire/Commonwealth intrigue you? Thinking of Britain's many political and so on differences with the rest of the EU its plausible they split away. The rest of the former Commonwealth will feel the need for power in numbers (thinking about Canada, Australia, South Africa + the minor ones, on their own they can't do much against an Chinese/American/IU/Indonesian aggression ). Then again I was thinking about their current population to size ratio (very very low for Canada and Australia), but in a century they could even triple their population ( I know Canada is gaining in pop. due to good living conditions and immigration). Good Luck!