You are, like most, overestimating Pep. He's not some kind of magician. He'll be fine without him.
Agendas are so fecking boring. Get a new obsession. Just to clarify, I did not imply Guardiola is a magician. Rather it was your assumption about what everyone else thinks about him that led you to interpret it that way. I think he has a lot of flaws too.
However it's abundantly clear that one of his strengths is in his ability to get teams to play aggressive, attacking possession football with an emphasis on making the right pass in key areas. He constantly berated Aguero for not doing that, and over time he has become much more likely to play that pass to his team-mate in the final third than go on a mazy run. That doesn't mean he has magically turned Aguero into David Silva with speed, he's still very selfish, direct and plays with his head down often. But he does that a lot less because Guardiola forced him to, by dropping him for players that would do exactly as he asked, even when Aguero was scoring goals for fun. The overall transformation of City is not hard to see, and the way they've transformed is entirely in keeping with his preferred style of play.
I believe the same to be true of Sane. He recognises the expectations that Guardiola places on all of his players on playing the right pass in the right areas, and that even for attacking players with sparking individual talent, just doing your own thing won't guarantee your place in the team. And the fact that everyone is singing from the same hymnsheet on that front makes it a lot easier to play those passes, because people then make the right runs, and the whole thing because instinctive and natural. Playing under Mourinho he wouldn't have the same expectations placed on him, nor would he have the same number of players in those positions to combine with, so he'd very much be encouraged to be individualistic.
Both Guardiola and Mourinho are at either end of that spectrum, and most managers Sane will play under hereafter (including Low) will be very much in the middle. So when he has those demands removed and he reverts to his natural game, it's entirely plausible that he'll be much more like Giggs than Figo in his decision-making and pass selection. If he ends up combining the best of them both then he's going to be a very special player.