The "4" minute intro can take care of singing, and creation of the World, but it cannot replace character building.... the intro of LOTR took care of the creation of the ring, NOT character building... But to make Children of Hurin, you need to explain, who is Morgoth, who are every other spirits, who fought one against another (Maia like Sauron) then you need to explain who is Hurin (youd do that in an intro???) then you would have to interrupt the whole ballad with another explaining of Hurin since in the ballad there is no explanation of Hurin's deeds, but only that he rides away with his army and is gone, then Morgoth hates his children.... this is simply insufficient.
The whole story cut out of Silmarillion really makes little sense, its a supplement of Silmarillion not a stand alone work like Hobbit could be used.
And to finish it off, its a story that ends in a terribly sad way.
Its just totally incompatible of usual filmmaking, just like Silmarillion is too grand in scope to make it into a 1 band movie or even a trilogy, just like Game of Thrones.