Funny how Commies only win in Hollywood and in fantasies 
They did all right in Vietnam, Korea and WW2 didn't they? and Cuba rings a bell too. But I'm not here to start a Commie flaming debate.
But the films premise, an invasion of the USA: Certainly possible. Succsessful ocupation of the USA: No chance in hell. A complete victory by the Soviets/Chinese over the US military: By sheer weight of numbers and some areas of tech superiority a severe possibility. But a complete defeat of the USA and total crushing of the population WITHOUT the complete destruction of the US government and population: Never in a million years.
Red Dawn makes a point, the USA and its military can be and more than likely will be overwhelmed and destroyed in the event of a Russian or Chinese takeover. But the American people will fight for every square inch of soil with every ounce of strenght they possess. And this is the message. Oh and my opinon on the casting is HORRID. Get actors who can actually act please.