Caf told me Fred is better than kante whilst some argued it. Now when kante is older and injury prone and Fred is in his prime he is surely better than kante. Right ?
Kante is on his way down as an all-action harasser and haranguer of the ball and opposing players - continually using him in this way will only hasten his injuries and degrade his output even more. He'll roll back the years and still have some performances Fred can only dream of per season, but they will not be the norm.
Unless he becomes a sitter who reads the game, conserves energy, and - most importantly - his body, consecutive games and runs of form are going to be a big ask.
Fred isn't better than Kante, but he is likely to be a much more reliable fixture than him; what you no longer can demand of Kante is to go out there and completely influence the game, it may happen, it may not, but it's not the default anymore. It's not prudent to factor Kante as a perennial starter anymore because he most likely won't be - he can be out for vital, season-defining runs of games, or even just be not up to par because he's not able to find his form so quickly after return from injury. Fred most likely doesn't have these issues, yet.