I think that the heart punch, along with hitting all the other vital spots can still be effective today if there are fighters are willing to learn it. Then again real effective body punching has become a lost art.

I don't think a fighter should imagine threats that aren't there, but I do think that in their training they should have a knowledge of the risks and opportunities that come off of a slip, or outside of an opponent's arm, etc. I think part of the effectiveness of Chavez is that there wasn't a punch/counter that he didn't know how counter himself, and he knew what he was getting into.