Podolski will only leave if we sign a player like Di Maria and a striker because he won't see much playing time then. I am sure that will harm his chances of going to the World Cup, it will make sense for him to move. Some rumours suggest it could be a loan for him to get regular playing time.
He is already second choice on the left and if Di Maria and a striker come in, he will be way down in the pecking order.