Devil's advocate.
First, "national service" does not necessarily mean relocation like a military deployment does. Second, there is no requirement that national service be free.
This has me thinking about a way to encourage some level of public service in exchange for better access to government programs, like an extra 10% in retirement benefits or something.
Reminds me of Starship Troopers: "Service Guarantees Citizenship!" Yes, I know it's a play on fascism.
> Starship Troopers
So, disclaimer: I'm very aware that Verhoeven created Starship Troopers satirizing fascism and holding up a mirror to American society.
That said, I am somewhat a fan of the idea that citizenship is something that should be earned. For example, birthright citizenship - I think it's a good thing and should be kept around. That said, as far as I know no natural-born American is required to raise their right hand and swear that they will take up arms to defend the United States in case of war. A naturalized citizen is required to do this. That creates a real bifurcation in the society in my opinion.