I think people underestimate Anthony. In fact, in a way, he's a lot like Michael.

Michael went against his father's wishes to continue college. What did he do? He joined the Marine Corps.
Then after the murder in the restuarant, Michael became the man he was today. (or..in the movie )

I think Anthony has the same air about him. He went against HIS father to do what he thought was right, or what he wanted. If push came to shove, I think Anthony could become as strong as his father.

And I think push came to shove when he saw his baby sister murdered in front of his very own eyes.