No one is saying that he's good because he's Brazilian though... You'd have to be daft to rate a player simply because he's Brazilian, especially when Brazil haven't been one of the top international teams for almost a decade now.
He can easily play with Chalobah. If anyone needs to leave it's Mikel. A midfield collective of Fabregas, Kante, Matic, Chalobah, Maia and RLC is pretty impressive.
Also, with rumours that Matic has Juventus interested he'd be a pretty sound replacement.