Its ironic that Nawaz Sharif speaks of rule of law. He seems to be forgetting that he was sentenced for his crimes by a Pakistani court and he got a freebie by posting an undertaking.
Once he gives up the undertaking , he would be back to where he started. He is perhapes counting on the Chaudry Iftikhar, Supreme Court Justice to find a way out for him. Chaudry Iftikhar cannot help him because the court action is completed and Chaudry Iftikhar cannot have jurisdiction over his last conviction.
Whats more ominus for him is ,that once his 10 year undertaking is over,the Pakistani Government can ask him to return to Pakistan to serve the rest of his sentence.
My sincere advice is just forget it.You got away with murders,don't push your luck.