Absolutely.It's ironic that the Tolkien estate is so stingy with the property because, in an encyclopedia I own, there's a foreword in it that states that Tolkien intended to have Middle Earth be a setting for anyone to make future stories, much like the Star Wars universe is today.
I noted above that he intended to create an alternative mythology for England that was less Francophile. And several of the scholars on the BTS stuff on the DVDs and Blurays mention this, and not just in the form of more and varied storytelling, but other kinds of contributions, like art and music. It was sort of to Prof JRRT's dismay that people so latched on to the core stories of Middle-earth that he himself wrote, when he wanted his works to be more of a seed bed than the flower itself.