Most shows tend to end permanently and in general it is a good thing to have a set story you're going to tell and then stop, rather than lurch on like a zombie for ages. While I know the desire to have more of a good thing, stories that don't end ultimately lose their appeal as nothing has any real consequences. In more episodic shows they start running out of unique plots for episodes that can be done with the characters and premise the show has. So I'm all for shows ending permanently at some point or another.