[Jody Barton]

Well the seats that are currently left open include:

Force India x2 (although expect Perez to be retained and Stroll to get his Christmas present from daddy)
Toro Rosso x1 (still talk Hartley might keep his drive, or Wehrlein will get his seat, the reason Mercedes released Wehrlein is so he'd have a shot at the TR seat)
Williams x1 (Supposedly a toss up between Sirotkin and Kubica)

So There is little chance for Ocon from what I can see. I expect Ocon to be named Mercedes reserve team driver at this rate, and probably given a fair few outings in FP1 next season, and then announced as a Mercedes driver for 2020. That's just my gut instincts. Still, it'll be sad that arguably the best Frenchmen on the current F1 grid won't have a drive.

Looking long term I think given the lack of seats drivers like Raikkonen, Grosjean, Magnussen, Perez, Bottas and Hulkenberg are going to come under increasing pressure to perform considering the wealth of young talent in F1. I personally don't see a place on the grid for the likes of Kubica, it would have made a great story, but it's just not going to happen, the guys injury was too severe and he's not recovered to anywhere near enough to participate in an F1 season in my opinion.