It's not about 40 yard passes to feet, it's about just being happy to play 1-2's and be on the ball for extended periods of time.
Watch this video
It's really not about starting attacks quickly or long range passes, it's about being an option for the passer all the time. So that when teams like Leicester or Liverpool or Spurs press high up, they get nowhere because you have an extra player.
I absolutely love Joe Hart, I want him to stay here until he's 40 - but you cannot see him doing any of the stuff in that video. The fact is that Guardiola needs a keeper who can do this kind of passing out of the back - it's fundamental to his system.
So that means
a) Hart improves on the ball drastically, after working with Pep's coaches and doing Rondo's etc.
or
b) we get a keeper who can play a part in open play.
I'd much rather see option a), but can't blame Pep for exploring the idea of a replacement. And that's why this would be a sensible purchase - Buy ter Stegen and hope that the competition and coaching from Pep improves Hart, then sell ter Stegen later if he really wants to be number 1, or Hart doesn't adapt and we've got a keeper who can play that way already, when he was on the market.