How much time in advance do writers typically get notified about a book being terminated? If you feel like you were unable to wrap up a story arc satisfactorily, are you still allowed to talk about how you would have liked the story to go?

DC is good about giving you time to wrap a story, they tell you well in advance so that you can end the book the way you feel it should end.  I don’t know the procedure elsewhere. 

It doesn’t matter how long some books last, there are always stories you wish you could have told!  :)