I highly doubt Castagna will play again this year. He was dropped after a game he got a lot of the ball (by his standards) and did some ok stuff. But he also did some peak George stuff, and I reckon Hardwick and the rest of the MC have decided/realised peak George is now too costly.
Assuming he is still on the list next year, if he can spend his off-season working to find the mental space that led him to be a key component of a couple of premierships, and part of a 3rd, and the mental space that led to less moments like the infamous smother. he may find his way back at some stage in 2023.