Well, I can't imagine it ending any time soon. But I can't imagine it 200 years in the future. I can't imagine Java as a used programming language 200 years in the future. RuneScape will eventually decline, to the point that Jagex can't afford to host it anymore. But, I don't know how it will end. If it does end, Jagex will still continue making other games though (Stellar Dawn, FunOrb, etc.). It's a sad thought though.