"Hogwash". To be more exactly, Daring Fireball reportedly said Steve Jobs answered "I think it's hogwash" when asked about a WSJ report that Apple's board was looking to replacement.
I agree. Apple isn't a company that you think will look for a new leader given the condition Steve Jobs is in without already having something planned. In fact, given the lack of any kind of actual evidence that Apple had before looked for a replacement for Steve Jobs, is looking for someone to replace Steve Jobs, or has plans to start looking for a replacement for Steve Jobs, the answer is obvious.
It's someone from within Apple. My money's on Tim Cook.