I know what you mean, but Cancelo has just signed a new, long-term deal and suspect this might be Walker's last season unless they open talks soon.
So we would still be light on the left.
Walker has 2 years left.
Mahrez is about to sign an extension with 10 months left.
I think there's an acceptance by all parties that after 30, contracts are shorter and signed closer to expiring.
Personally I don't see Walker being any less vital to our defence next season, and would be amazed if he left before his contract expired in 2024. If I had to put money on it, I'd put it on him extending to 2025. It might depend on where Sheffield United are at the end of 2023/24.