According to the Shirley Oracle in an article on Ben Affleck's on his new film Truth, Justice and the American Way, they also mentioned another movie he might be doing.

The article stated,

"Word is Affleck is in final talks to join Bruce Willis in the $130M blockbuster Die Hard 4. Willis, who reprises his role as singlette- adorned law-man John McClane in the film, has been beseeching for a project to work with now good friend Affleck, whom he co-starred with in 1998's Armageddon with, for several years - initially suggesting him for Tears of the Sun.

When Affleck was unable to do that movie they idea of them working together again was put on hold, until Willis was asked for some ideas on who he thought should play his son in Die Hard 4.

Affleck would play the son of John McClane and would assist his on-screen dad with whatever villians he might be fighting in this new installment of the Die Hard franchise.