It would certainly save Mercedes about £50 million. But is that the thing they'd want to do in this climate of diversity? They've gone all out for a black livery in support of the Black Lives Matter cause, and no matter how much replacing Lewis with George would be a financial and not-a-loss-of-performance reasons replacing Lewis with George would be, it would be a PR disaster that they could not recover from. No matter how much it wouldn't be for Lewis' colour, you know there are a lot of people on Twitter who would cancel Mercedes for that reason - especially if they keep the black livery next season without Lewis.
You don't get rid of a 7-times World Champion who's just won 4 titles back-to-back in your car. If he goes, it's on his terms. A large pay demand isn't enough to say no to - Lewis can pretty much demand what he wants because he is such a star that the team will make that money back pretty quickly from Merchandising and Sponsorship deals Hamilton can bring in.
Hamilton doesn't sound like he's done with F1. If Mercedes isn't an option, he needs to get on the phone to Horner and Marko ASAP to replace Albon at Red Bull. TBH, Red Bull need someone like Lewis to get back to the top. Max might have the speed, aggression and passion, but he seems to be the kind of driver a team bows down to and does what they want for him. Lewis is a worker and an inspirer who works with the team to improve. It's what Schumacher did and it's what Vettel did when he won all his titles at Red Bull (which is exactly what Aston Martin are hoping to get from Sebastian). Perhaps someone with Hamilton's teamwork mentality is what Red Bull are missing.