What is the expected result of kicking out and rejecting all immigrants?

And by immigrants I really mean immigrants: you don't have the nationality and live in the country = you're an immigrant.

I keep reading about the plans of parties to kick out all immigrants, stop letting in any, and some parties even advocate to revoke dual-nationalities and kick those people out too. I've never really understood what the point of it is and have trouble imagining what the effects of such actions would be within the country.