Your car is never going to break down completely because of it.
You'll notice a loss in boos pressure (if you have a gauge), if not, then a loss in power.
Also a drop in MPG is noticeable.
I have a revision G on order from VW at the moment as i, also, have seen no evidence of it ever having been changed. Besides, for the sake of £35, i'd class it as a consumable and check it with my servicing every year and replace it necessary.