Die Hard 5 A Good Day to Die Hard Movie

The official title of Die Hard 5 has been revealed: it's "A Good Day To Die Hard". There's also an official plot synopsis:

Plot:
"Since the first Die Hard in 1988, John McClane has found himself in the wrong place at the wrong time, with the skills and attitude to always be the last man standing, making him enemy Number 1 for terrorists the world over. Now, McClane faces his greatest challenge ever, this time on an international stage, when his estranged son Jack is caught up in the daring prison escape of a rogue Russian leader, and father and son McClane must work together to keep each other alive and keep the world safe for democracy."

What actor would be fit enough to play John McClane's son? Any idea who they're going to cast?
:)