This question comes up every couple of months or so. The screenrights encompassing The Hobbit and The Lord of the Rings theoretically allows for spin-off films derived from the books as long as they don't infringe on material that is exclusive to Tolkien's other books. There is certainly some material in the LotR Appendices that holds potential for more films. My favorite example would be a movie about the great journeys and errantries of Aragorn, base on "The Tale of Aragorn and Arwen" in Appendix A.

Before the LotR movies, lovers of the books like me were dismissed as nerds. Then when FotR blazed unto the screen, there were a few years when it was trendy to be a Tolkien fan, before that inevitably faded. For The Hobbit movies it was all been, there done that, and Tolkien was no longer cool, except to genuine book and/or movie fans. Nothing has really changed.

I have been a lover of Tolkien’s books for almost fifty years and the movies have existed for about a quarter of that time. I never cared that the literati dismissed the books in the decades before 2001 and I don’t care what the general public or critics think now. For me the books are a separate entity from the movies and the latter are just another version of these stories, seen through another artist’s eyes. The books are still there to be reread.

But you know that the Adventures of Aragorn would inevitably also feature Legolas. I would be all right with that, though most would probably hate it. Bloom would probably get star billing because they would have to recast Aragorn.

My own favourite notion is a companion piece to LotR about the other parts of the War of the Ring, especially in the north. I would love to see see Brand and Dain defending Dale and Erebor, Thranduil's battle against the forces of Dol Guldur and even the assaults on Lorien. It's too late to do Saruman in the Shire.