>why shouldn’t it be in Sweden’s interest to one, either stop the flow or alternatively take control and annex Denmark in order to bring it into the fold?

Because Sweden is not ruled by a dictator? The moral thing to do would be for the government to ask "jeez, what are we doing so badly that half our population is telling us to fuck off?" and implement policies that give incentives for the population to stay there. The immoral thing to do is to go full iron curtain.

>In any case, I see it eventually resulting in a new colonialism where elites and businesses are the main ones deriving advantage and wealth from this new arrangement. Localities lose power to distant and disconnected power.

So would you advocate for the borders between US states to close down and all citizens to require a visa to change states within the US?