[William Cloud Hicklin]

Theoretically, it could be done (although use of the title 'silmarillion' would create trademark problems independent of copyright concerns)

However, your hypo film could not include-

-the Music of the Ainur
-any description of Valinor
-any Valar save Varda and Morgoth
-the awakening of the Elves
-the House of Finwe aside from Feanor
-any details of the Darkening, such as Ezellohar or the Ring of Doom, or Ungoliant's presence (Ungoliant's existence as an ancestor of Shelob could be deduced, but no tale or incident involving her whatsoever)
-any mention of the Oath or the Kinslaying
-any description of Thangorodrim
-the founding of Gondolin, or Turgon's ancestry
-the founding of Nargothrond or any description thereof
-Any of the Five Battles of the War of the Jewels
-Fingolfin's duel with Morgoth (identifying the original Grond as 'the Hammer of the Underworld' doesn't go any further than that)
-any part of the Tale of Turin
-any part of the Tale of Tuor
-any part of the Tale of Tinuviel, save the specific elements related by Aragorn
-any part of the Fall of Doriath or the sack of the Havens; indeed no mention of the Havens at all
-any part of the Tale of Earendil except for whatever can be squeezed out of Bilbo's Song

and on, and on, for 400 pages of the Silmarillion.

So you're trying to write a film script derived entirely from a one-paragraph synopsis. In other words you'd be in the same situation as the rather funny attempts in various fan-newsletters, pre-77, to predict The Sil's contents.

Likewise, a film of the Fall of Numenor could be cobbled up from Appendix B, but no mention at all could be made of the details found only in The Akallabeth, like the Temple of Morgoth or the voyage of Amandil.