Ok, let's say that is correct, how it does answer my question?
Fluid football are present since Rinus Michels at least. Do we credit all systems and coaching style that has certain fluidity to him? Or whoever started it before him?
So basically, Crujif, Ten Haag, Pep, Klopp, Naggelsman, Flick, Tuchel, Lucho are all Michels students whose roots and DNA are to him?
No, I credit everyone that implements it well within a certain setup. Ten Hag is his own thing, Klopp, Pep, Xavi if he makes it, Nagelsmann if he makes it big etc. If they want to publicly mention Pep as a huge inspiration for them, fine, this only makes Pep the leading manager of his generation and one of the best of all time (which he no doubt is), but it doesn't mean that they are Pep copies even if they do mention Pep as a mentor for them in their early career.
The ideas can't be that new, everything being done has been done before in some form or other. Football is very old, nearly everything we see has been done already. Barca DNA is a made-up term, I barely ever use it myself. And the idea that possession-based football can't work anymore is dumb as hell. It will forever work. That's like saying opera or rock music doesn't work anymore. They will forever work until music disappears altogether or everyone goes deaf. What can't work? Pressing hard, high line, false 9, quick passing? If you know how to make them work, they will work. If you don't, they won't. These are ever-present in nearly all the best sides in the world almost because they know how to generate the conditions that make all these ideas viable.
Nobody knows any concrete thing about Xavi yet. Projections are mumbo-jumbos. Positive predictions are based on the illustrious career of Xavi as an extremely tactical and cerebral player (mine is anyway), and negative projections are based on some half-baked ideas such as "Barca DNA" being obsolete, as if Barca DNA is some sort of gadget, like old LCD screens being replaced by OLED panels.