This one will stay on board until the end. He probably wants something new, rumors are that he may be eyeing a ruling position at Rosgvardia. Still, even if he goes through with it (this isn’t the first time when he “threatens” to leave), he’s still going to be a de-facto ruler of Chechnya.
No way is Putin going to try and replace Kadyrov in the middle of a failing military campaign. Chechnya gives him tons of fighting personnel and he can always be sure in Kadyrov as far as he gives Kadyrov what he wants (autonomy and money). Trying to replace Kadyrov, who is an even more ruthless autocratic dictator integrated in every sphere of life in Chechnya than Putin is in Russia, is a suicide — he’ll get a Third Chechen War as a bonus to the Ukrainian front.