#3 Esteban Ocon
With Lance Stroll's billionaire father involved in a consortium takeover of Force India, all signs point towards the Canadian driver leaving Williams for the Britain-based team. That would mean that one of the two drivers currently racing for them would have to be given the boot. Ocon has impressed in his two seasons so far, but Perez is the more experienced of the two, and with the team needing to raise significant finances he could be the more attractive option given the brand appeal that he has in North America.
Ocon is a protege of Mercedes' Toto Wolff, but with Lewis Hamilton and Valtteri Bottas already signed up for 2019 there is no room for him on the 2017 world champions. The Red Bull seat is open, but they prefer to promote from within, and few other seats look available if he wants to race in F1 next year. A straight swap with Stroll would be another option but Williams is currently in a far worse place than Mclaren, for all the problems they've had.