I don't think you'll see a non-licensed pinball for a very long time, if ever. I guess it's a money risk thing, Stern seem to go with their biggest target market, machines that will be easily recognised by the masses and appeal to most. Remember Batman was called Batman not The Dark Knight so it appeal to more people, earn more money,blah, blah blah. Being the only true manufacturer of pinball at this time there is no competition and they have no need to change their ways and unfortunatly pinball at this time has a small volatile market so Stern will stick to the sure bet. I'd love to see some original non-licence machines being produced, and the only way I see this happening is with a larger fan base and competition in the pinball market. I think Stern ARE doing a great job and all we can do is spread the word, share your passion for pinball with others and hopefully in the future things may change for the better.
I'd like to see Sterns next effort be a Futurama licence, also heard that Tron could be on the cards too.