That's really what Red Dawn is, isn't it? It's the underdog, a handful of kids led by a few soldiers that kick the collective butts of two highly trained foreign invading armies (in this case North Korean and Russian). Did these invading armies not think things through? How silly to invade America when every citizen is a potential soldier, right?
While the biblical, David vs. Goliath theme is often present in these types of films, you really have to suspend your disbelief to accept the premise.
I don't accept the premise and I don't care to see this remake.