Back to the OP's "...and he will!"
So, from here, Federer has to collect 3000 points (win Paris, London and Basel) before the end of the season. On the other hand, Djokovic needs 756 points in Paris + London.
Possible for Federer...
If I were you, I would also be concerned that he may finish at #3 this year since Murray is defending 180 points and is definitely playing his best tennis...