I'd probably go something like this for the AO:
Djokovic: 45% chance
Sinner: 25% chance
Alcaraz: 15% chance
Medvedev: 10% chance
Rune: 4% chance
The rest of the field: 1%
Cahill has overhauled Sinner's mechanics for the serve. His feet are spread out a lot more and he has a much more efficient motion now. He's not swinging wide, which allows him to be far more accurate. In addition, he appears to be jumping a few more inches off the ground, which allows him to hit with more pace these days. And this all happened this Summer. And Sinner is going bigger on break points. His average 1st serve speed when facing break points has jumped from 122.9 mph during the first half of 2023 to 125.0 mph during the 2nd half of 2022. That's a big difference. And it shows. For the first half of this year, his opponents were converting 34% of the break point opportunities vs Sinner. During the last half of the year, that number plummeted to 25%.
And Sinner is still a work in progress. He'll only get better.