No. 5 - Aston Martin
Like Williams, Aston Martin has emerged as a possibility for Carlos Sainz Jr. as a result of Lewis Hamilton's move, and it is based on the idea that Fernando Alonso could end up taking Hamilton's place at Mercedes and thus free up the two-time world champion's current seat for his fellow Spaniard.
But this scenario seems far less likely since there doesn't seem to be much of a chance for two vacant seats like there is at Williams. Alonso would have to leave, and Sainz would have to be the primary target.
Alonso making any move is likely contingent on him not being satisfied with Aston Martin's progress, and they are coming off of a 2023 season in which they were competitive with Mercedes throughout, so it's far from a given that he would even want to leave.
And then there is Lance Stroll, who is likely going to continue competing for the team as long as his father Lawrence is the owner.
So logically, the only way this happens if Alonso doesn't leave for Mercedes is if he does leave for Red Bull to replace Sergio Perez. I guess given what we've seen with Hamilton, you can't rule anything out.