A new one-year deal for Zhou and exercising a contract extension option for Bottas has left Sauber junior Pourchaire to stay put as reserve driver.
Pourchaire won the German F4 crown, was the 2020 F3 runner-up and ranked second in F2 in 2022. He is poised to seal the 2023 title in Abu Dhabi, leading Mercedes junior Frederik Vesti by 25 points ahead of the finale.
Pourchaire will join the past two F2 champions Felipe Drugovich and Oscar Piastri in missing out on an immediate F1 promotion. However, a race and possible test programme look likely, according to Sauber managing director Alessandro Alunni Bravi.
Assessing Pourchaire's future F1 options, the Italian lawyer said: "We are ready to make a deal.
"We are discussing together which will be the best racing programme for him to be ready to jump into the F1 car. No doors are closed for him in the future.
"We have seen with Felipe Drugovich… Piastri as well that, after one year in Formula 2, if there is no actual chance to be a race driver, this doesn't exclude the possibility for the team to appoint in the future."
Drugovich, a contender for the Alfa seat alongside Bottas, has served as an Aston Martin reserve driver. He has reportedly turned down IndyCar offers and is thought to be a leading candidate to replace Edoardo Mortara at the Maserati Formula E team.
Piastri, meanwhile, undertook an extensive F1 test programme for Alpine in a 2021 car before his fractious switch to McLaren for 2023.
Alunni Bravi said Sauber would consider a similar test programme for Pourchaire but that finances for the Swiss squad may be the limiting factor.
"We just need to look at what is the best programme for him," he continued.
"We want him to stay close to the F1 team because this year we asked him to be fully focused in Formula 2 and he's doing well.
"I think and I hope that he will win the championship in Abu Dhabi.
"Maybe we can also see for him which will be the best to be ready and to be prepared.
"We don't have an old car like Aston Martin, like McLaren, or Mercedes to do a proper testing programme for a driver.
"This is a big limitation - maybe this will be available for him next year.
"We are discussing internally. Of course, budget-wise, this is something that for a team is quite expensive, but we want to see all the opportunities. For a driver like him, the doors are open."
To fulfil the requirement to field a rookie in at least two practice sessions, Pourchaire will likely drive the 2023 Alfa F1 car in FP1 in Mexico and Abu Dhabi.
