Mercedes want Antonelli but are unlikely to be able to get him until he at least finishes his F2 season where he's not setting the grid alight, although his team Prema are struggling to understand the new car.
This means any seat at Mercedes would likely be a 1 year, perhaps with a further year option so consequently no one wants to go there for such a short time with most seats and drivers tied up long term. Ocon is a possibility, Toto loves him and, I think Toto is still his manager although I'm not sure.
Alex sees what's going on behind the scenes as Vowles is driving significant change inside Williams and Dorilton are investing as well. I don't think Red Bull was an option for him either as Perez will likely be re-signed.
Sainz should really go to Audi but make sure it's a three year deal so he gets 2 years with Audi to see how they're looking. His offer there is a big one apparently, something red bull said they couldn't match.