Hanyu - Until the most recent interview he has been saying that he hasn't made any decision yet. He might just compete and see how things go, like two seasons ago he was almost sure he'd retire after Pyeongchang, but now he's definitely staying.
At the press conference after Oly fs, he said that with the 2nd OGM his dream's come true, and what's left is 4A which is "a goal, a childhood vision, not a dream." According to people from his team, 4A might come as early as next season, so what's after that? Like BOrser said, Yuzu always needs a goal to go on, so we'll see if he finds a new one. (Doesn't a third OGM sound appealing Yuzu?)
He's still so young (think of Kolyada who's same age as him and "just starting"), but also had so many injuries that are unlikely to heal completely.
Another factor that might come into play is the new scoring system. From what we've heard, as long as they stick to the rules instead of start throwing candies right away, I think it's pretty in favor of Yuzu.
Medvedeva - She's stated clearly that she intends to go for 2022. While there're legions of young Russian girls, I think Zhenya has the advantage of a) having already survived puberty, and b) being very consistent and reliable. These factors make me think that she'll have an 2022 Olympic spot, even though I can't say if she'll be the favorite. Also, she's training a 4s, which she's rotated but have issues with landings.
Chen - His going to Yale instead of a Californian college has made things seem very unclear for me. I just don't see how anyone can manage to study pre-med full-time and stay on top of a highly competitive sport at the same time, not to mention being thousands of miles away from your coach. He seems to want to do that, but apparently hasn't discussed with either Arutyunyan or Yale yet.
Didn't work for Stolbova, Kavaguti, Moore-Towers - all very determined skaters. 
