I see it as more a political statement by George Miller.
I think he perhaps wishes to convey how visually lazy a lot of modern movies are and perhaps, yes too many movies rely too heavily on dialogue. He can do this while holding an armful of awards. And rightly so.
A film that I am also very fond of is “All is Lost” with Robert Redford. There is very few moments of dialogue the story is told through events that happen and facial expressions and desperation. It conveys the sense of being all alone and in big trouble, trapped.
“Buried” is another good example of a film that uses Dialogue quite sparingly again alone and trapped.
Mad Max Fury Road - It does not fit in to the same mold of being alone and trapped, and personally I think he did an amazing job with the film he delivered theatrically and technically.
I am not trying to influence your opinion before you see it, but I am interested in it also. I just feel a bit skeptical about it, not saying I would not like to see it personally but I am not sure I will enjoy the film as much as with the dialogue. The Black and White does not bother me in the slightest. Without the Dialogue you miss a lot of the culture of “that world” and no Mad Max film has ever been silent before.