400M is a great deal for Vlad.
If he repeats 2024, he could get higher, but I don't think it will be much higher. He'll need to have some sort of Judge-like walk year where he raises his game to completely new levels to get a ton more than 400M.
If he gets hurt or repeats 2023, then he's looking at a little bit better terms than what Pete Alonso just got.
I think with recent leaks revealing how close they are, he's trying to get more but it's squeezing blood out of a stone at this point. Maybe he'll get another drop but I think the deal will get done before Opening Day.