There is a pretty good shot of the incident from the crowd, Vettel is going very slowly Kvyat was going slowly and a Toro Rosso, maybe both of them, were going much faster than Kvyat behind him and almost hit Kvyat. Vettel slowed, Kvyat slowed just not enough and Vettel was a pretty big distance behind Perez, more than far enough behind to not slow down as much as he did.
China was plain great racing, he got a podium with a car that wasn't really fast enough for it based off that move, it was a great drive. Yeah, Russia was bad but every driver has bad races.
I would bank on this being 98% because Jos is negotiating with Ferrari/Merc/Mclaren and said to Horner in the past two weeks, give us a seat now or we're signing a pre-contract with whichever of those teams was offering the best deal. I think Kvyat is decent and has a decent career ahead of him however top teams wanting to win championships need to secure drivers like Verstappen, if he's not with you he's against you and he's the kind of driver who looks capable of stealing titles from you when he's with a different team.
I also think Kvyat being Russian plays against him in a worldwide fan, team appeal sense. Russians speaking english sound very, un-natural, almost uncomfortable. Verstappen sounds far more relaxed and clear speaking English. Ricciardo is loved by fans everywhere, as much as winning and speed on track is important, ability to do well in a room with sponsors or in front of a camera to engage the fans is very important. Ricciardo/Verstappen as a pair will do better in all aspects on and off the track than either with Kvyat.