I'd rather it never happened, at least not as a film-its a book primarily written for hardcore fans, and I can't see a film retaining this, yet still being commercial. Not only is very complex (meaning most of the dialogue and structure would have to be re-written...it would also require a collosal budget) its more or less unconnected to the angle Jackson's films have taken, and with its grim tone (it features incest and mass murder-with betrayal and greed being the main catalysts for the plot) and the fact that almost no LOTR characters are featured it would be extremely hard to market and still please fans and novices at the same time.
Tolkien himself doubted whther readers would find the sil interesting, for people weaned soley on the films this would be even more true ('Wait so Elrond's dad is the magical starlight that Frodo uses to fend off shelob in ROTK film???). Its also something very personal to Tolkien (Beren and Luhtien were engraved as his and his wives tombstones-and his religous beleifs are very evident) and is really more of a historical chronicle than a narrative.
That said as high budget TV series such as Game of Thrones etc, it could work:
This would give the producers more room, and time to tell the stories, whilst allowing to make it for a diferrent audience. With the increased time and detail a TV series would allow it would also be alot closer to the book.
Personally I hope it never happens, but it I was given a choice I'd vote for a TV series (incluDing relevant stuff from Unfinisihed Tales and the HOME)- with Peter Jackson and co still writing...BUT
I'd also like Christopher Tolkien (or other Tolkien accademics such as Tom Shippey or Robert Foster) to be direclty involved in execuitive producer and screenwriting roles-you get the best of both worlds, Jackson's visual and storytelling no-how plus the advice and guidance of the Tolkien estate.
