For whatever reason, say America does worst in the War of 1812, leading to the British (Who never saw the Louisiana Purchase as legal.) to take Louisiana. Leading to either...
1: Louisiana is given back to Spain with New Orleans as an Anglo-Spanish condominium.
2: Everything of Louisiana from 42°N and above is attaching to British Canada while spinning the rest off as a pro-British state or a separate British colony run from New Orleans.
Could this happen? And the result from any of this?