In the Dark Knight, does Lucius Fox resign?

Im am thinking he doesn't because he is shown typing his name while Batman is saying his speech about people deserving to be rewarded for their trust, and it looks as though the machine self destructs because of the sparks, but is he leaving for good? Also, if he does resign, how would it be possible for Batman to exist if he successfully runs the enterprise and is the genius behind all his weaponry. People like Lucius Fox don't come around every day, and it would be nearly impossible for Wayne to have separate people for his weaponry and to run the business. He would either have to entrust someone to know his secret and never tell, or he would keep it a secret, and the business person would wonder where the spending is going for all his gadgets, so it would be almost impossible to have two people running each operation.