He can only take Valterri's next year. From a Merc perspective, I remember thinking after the Bahrain race, filling Hamilton's spot with Russell just to have Bottas continue to be the perfect second driver would be gold for them if Russell really delivered on his potential. But a Lewis/Russell setup could be a risky but necessary affair, especially if Russell can possibly outdo Hamilton and he's not prepared to be treated like a #2 driver and Red Bull/Verstappen don't let up. Russell should want to take Bottas' seat and beat both Hamilton and Verstappen if his goal is to prove he's that good right now.