With both Bearman and Kimi more or less confirmed for F1 next year according to rumours the amount of seats available is shrinking fast, but I also think we'll see lots of departures. Presumably Sergeant is out, as is one or both of Zhou and Bottas. I would be very surprised if Ricciardo manages to cling to a seat, and I could see Magnussen going too, possibly.
Ocon is alright in terms of speed, but his teammate track record is going to be against him and he also doesn't bring any sponsors as far as I know. I wouldn't be shocked if he ends up without a seat, but I can also definitely see him going to Haas or maybe Williams.