It's a dead man's switch, if new episodes don't keep getting released, its assumed that the USA has fallen and by the computers monitoring, and the nukes are automatically launched.
Honestly, this makes the most sense to me. I never really hear about the Simpsons now, and don't know anybody who watches it... It feels like it's just being put out into the void right now.
The cast is going to start dying off en masse soon. Harry Shearer is 79. I don't want Harry Shearer to die. I was watching A Mighty Wind just last night. But he's 79.