He're my take on the end.
Norman Arbuthnot, the right-wing leader, shows the dinner hosts that they have betrayed their own principles by failing to engage in intelligent debate with those they disagree with (the Hitler question). While they're in the kitchen he discovers they are commited liberals (the Mondale book) and are killing right-wingers like himself. Luke (the black guy) meanwhile, says that Arbuthnot is going to be the next Hitler and should be killed. His friends convince him otherwise and they go back to dinner. It looks like Luke was right about him though, as he kills off the guests even though he has already pesuaded them by debate. The end of the movie suggests that Arbuthnot is on his way to becoming the next US (Hitler-like?) president.
A Freeper goes by the name of Norman Arbuthnot. I'll ask him for his interpretation.
That's a new perspective.