Seth MacFarlane is a guy who knows how to keep a show running for years. Family Guy has been going since 1999, American Dad started in 2005, and he sees his live-action comedy show Ted going for just as long, with one condition. They need to keep funding the CGI bear.
Speaking with Collider, MacFarlane explained why certain shows feel like they can go on forever, while others look like they're heading towards a definitive conclusion. "There are certain series that are premise-based and other series that are character-based, which is how television operated for decades. You watch Friends, you watch The Office, those are character-based shows. If something is character-based, it can go indefinitely because it's whatever situation you choose to put these people into, because it's the people that your audience is showing up for," he said.
"Ted is a character-based show. The only thing that hinders us is the expense. To create the bear is a lot of money. But you have these fantastic actors, you have this fantastic writing crew. You can do as many as you want. I mean, you could do 20 seasons of this thing, and it would work, but you have the CGI element that makes it challenging. But story-wise, to answer your question, it can be indefinite. There's no limit to the number of stories you can tell with characters that people want to visit week after week."
MacFarlane described making the CGI bear in Ted as "doing a Marvel movie like once every half hour," so we're guessing it's not cheap to bring the eponymous bear to life. So long as Ted succeeds enough to fund the bear, we'll see more of him.