A while ago Fillion said in an interview (maybe Kevin Pollack's Chat Show or Nerdist) that he pitched a story about a sci-fi convention and the star of a long since cancelled show gets murdered and all of his fellow cast mates are suspects. He wanted to essentially have a Firefly reunion, and since Tim Minear is an EP on the show, and they aren't shy about throwing in some Firefly nodds... I don't know if that'll ever get made, but I would love to see that.
It sounds very similar to the soap opera star murder episode we got.
As for the episode, I have to say that I was not really blown away. I didn't feel any tension when they were trying to save Kate's life because it was pretty obvious that they weren't going to kill her off. As other's have said the new Captain is very clichéd but there were a few scene's I sort of got the feeling that she "gets it" and is just doing her job. Still, I would have preferred to have seen Michael Dorn as the new Captain. When I saw his name in the credits I was hoping that's what we would get.
I also felt the show was pretty predictable. Another season premiere where they don't talk all summer but you just knew they would make up in the end. And as soon as Kate froze up the first time she had to draw her weapon you knew there would be a scene later on where she'd redeem herself. I also don't think the darker tone works for the show. What I like most about Castle are the interactions between the team when they're working a case and the humour. I know they like to inject a little drama to the show once in a while but they are definitely not my favourite episodes.
Still, I look forward to seeing how the season unfolds. I hope we get to see of Michael Dorn too.