Interesting thought - I suppose the rights to the earlier works would have to be purchased from the Tolkien estate? Perhaps someone already optioned them years ago.
I don't like how he changed the Hobbit - but I would still love to see more of Middle Earth (especially the Undying Lands, Beleriand, and Numenor!).
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I would too. It's a rich universe and it would be a shame if new stories weren't created. They could be based on The Silmarillion.
But I think Jackson could continue making movies based on other book series; series that were inspired by Tolkien. There are plenty of great ones that have devoted followers. As a fan of The Wheel of Time, I would obviously love to see a film made of it.
Funny thing - I read all the WoT books, but stalled out on the final volume! It was such a huge investment of my time. Once I started reading GRRM's books - I couldn't get into WoT any more.