Cas will be in the stories for sure, it’s just that he’s twisted up in Main Plot things, and so must wait for his time. But he will appear, and a lot of explanations for what has happened to Sam (both brothers in BL and BC) will be given at long last.
Celeste has a plan, and no one will stop her.
(Try not to send in duplicate asks! We will get to them, but unfortunately with full time jobs it’s difficult to answer things as they come in, which is why we schedule the asks to post. A flood of the same question will not make us post it faster.)