Luke Skywalker is the chosen one!

[Jedi_Monk]

But then again, you could wonder why Qui-Gon knew of this prophecy at all if the sith was belived to be extinct for the past milennium. I doubt that the jedi from the sith wars thing expected the siths to return, so why should they teach this prophecy to the younger ones at all?

Think about it this way: What is prophecy? Here's the dictionary definition:

1 : an inspired utterance of a prophet

2 : the function or vocation of a prophet; specifically : the inspired declaration of divine will and purpose

3 : a prediction of something to come

Okay... so some Jedi, inspired by the Will of the Force (the Jedi divinity), predicted that a Chosen One would come and bring balance to the Force. This is the Force speaking through the mouthpiece of some Jedi. When your divinity speaks--even if it's something that seems like it would never happen--wouldn't you continue to teach it?