A lot would depend upon how the side evolved, and if the style of football changed.In a way, it's a poisoned chalice. If the new guy comes in and wins the PL, it'll be "well; Guardiola won 6 of them". That's why the Moyesiah was destined to fail at "The World's Greatest Club"™; he was following (like it or not) an outstanding manager. That last title they won; it was a bang average squad, but GPC got them over the line. Signing Van Persie helped, mind. Without him, they wouldn't have won it. See Moyes' first season, with pretty much the same squad?
Pep early sides were incredibly exciting on the eye, pace, wingers lot's of chances created and devastating counter attacks.
That's evolved and become far safer and more machine like, at likes this last season it was often dull with constant possession but few chances created.
Someone could come in a tweak that somewhat, but whoever does come in after Pep is going to have to go some to get any recognition.