It's surely just a means to an end, though? Xavi won't go on forever and Fabregas could easily play that role, I'd have thought. Playing him in the false 9 position probably happened because Cesc has had a few good goalscoring spells at Barca and needed the game time. I don't think that's where they see him permanently.
Totally disagree. He's a very different player in terms of style. Unless they change his game drastically, he'll never play the Xavi role as effectively imo.