Some folks get to worked up over a show. They may need to sit down, take a deep breath and repeat to themselves, "it's a show, I should just relax."
As for season 4 being the end, maybe, but maybe it'll have 5, 7, or more seasons. I'm enjoying it as long as it lasts, as long as the writing is at least as good as it has been so far. Some episodes I may not like as much as others, but when you have as many as the show has so far, that makes sense.