I think this "idea" (that a rock star is many people/faces) has already been done (unsuccessfully) with the Lennon broadway show. The Scorsese documentary (while not perfect) already covers the ground of Bob's early career amply.
And Bob himself already did this in Reynaldo and Clara by having other "actors" play "Bob Dylan." Enough already, we get it. He's not who "he" is. But is there any more to the story than that? A much more radical version of the Dylan biopic would be a straight old hollywood biographical extravaganza like George M. Cohan in "Yankee Doodle Dandy" or even something like the original "Jazz Singer."
Now that would be mind-blowing!
But instead the Hollywood folks will be able to look down on/put down middle American with some imaginary folks in Peoria saying: "Hey, look, maw, they done put in another actor playing that weird little skinny fellar who's what this movie done be about."
We seem to live in an age where flash definitely trumps substance. Poor Bob. Or should I say, Bobs.