This is no fun with no devil's advocate, so let me help!
I predict that in 200 years or less countries will be competing for citizens in a global marketplace, in the same way that they do today for businesses and their taxes, or that companies do for talent. A generation ago people thought you should/must be loyal to your employer, but now people are realizing that's ludicrous and have no problem bailing if a better opportunity presents itself. My guess is that this will be routine among countries and their citizens in the future. Countries won't like it, just like businesses don't, but opinions will ultimately shift in favor of permitting it, just like businesses do (ie theyve adopted an "if you can't beat em, join em" mindset and hire people with job hopping pasts).
Flame spray away.