My own prediction is for five seasons. I say this for three reasons:
- Salaries tend to rise every season a show is on the air, which makes the show less and less cost-effective to produce.
- We know that CBS is nearing the maximum number of Trek shows it wants to simultaneously produce, and is holding back other concepts (like Section 31) until something goes off the air.
- Perhaps most importantly, pretty soon it will no longer be clear Discovery is the flagship Trek production. For a long period of time, CBS had to be committed to the show because it wanted to revive Trek in order to get its streaming service off the ground, and everything else was years behind in terms of production. But by 2022 we'll be into Picard's second season and Strange New World's first - not to mention the animated shows. At some point one of them is going to surpass Discovery in terms of popularity, and the show could be in serious danger.