Xavi recently said he has no intention of hanging up his boots in the immediate future.
However, the midfielder is now 34 and Barcelona will be aware a long-term replacement may be required sooner rather than later.
Fabregas has been earmarked as someone who could possibly fill the deep-lying playmaker role that Xavi has enjoyed such success in.
Yet the 26-year-old does not envisage that being the case, and feels Barca will be forced to adopt a different style of play once the "unique" Xavi does step aside.
Speaking to RAC's 'Your Say' programme, Fabregas said: "I don't see myself replacing Xavi. Xavi is unique.
"No matter how hard we look, Xavi is a one and only. Whoever replaces him (in the starting XI) will have to be very strong mentally and the team and the fans will have to get used to playing differently.
"The day Xavi is not in Barcelona we will see a different team. I don't know if it'll be better or worse but it'll be different for sure."
Fabregas also stated his belief that Barcelona can complete a treble by winning La Liga, the Copa del Rey and the UEFA Champions League this season.
Barce have slipped to third in the title race, four points adrift of leaders Real Madrid, following a 1-0 defeat at Real Valladolid last Saturday.
Gerardo Martino's men bounced back quickly, however, by securing their spot in the Champions League quarter-finals with a 4-1 aggregate victory over Manchester City in the round of 16.
And with a Copa del Rey final against Real on the horizon next month, Fabregas is targeting success on three fronts.
He added: "The way we played against Real Valladolid wasn't acceptable for anyone in the Barca shirt.
"It's not good for anyone that our performances can be so different in four days, but we played with great discipline against City, which we didn't against Valladolid.
"I was worried that the criticism of the team would harm us but that's not how I saw it work out. I saw a team wanting to put it right.
"We will give everything (for the rest of the season) and we can win all three competitions."
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