Cue Obama and his acolytes complaining about "abandoning" the cities. The Left has already floated trial balloons for things like exit taxes. It all proceeds from the premise that you property and earnings aren't your own, therefore you can't just up and take it with you.
That's why everything in communist countries ended up being coerced, because the economic system was so wholly unnatural that the only way to make it even partially viable was to dictate every aspect of a citizen's life. Where to work, where to live, what job function. The liberals here would absolutely exercise the same degree of control if they get the chance.