I think Miller and JR jr are the ideal people to refine and refresh Superman’s origin, especially after what they did on the similarly-conceived Man Without Fear Daredevil series so many years back (which I still think is hugely underrated).
I don’t really expect them to violate continuity in any drastic way, but the freedom from ‘canon’ should allow them more flexibility to do exactly what they want. I’m hoping that Miller’s traditionally direct, bold and dynamic storytelling style and JR jr’s similarly bold art will make this story really move, in a way that isn’t true of all retellings of the origin.
There have been lots of takes on the Superman origin, even recently* but I still think we’re waiting for the definitive modern version. There’s stuff to like in all of them, but it feels like there is room for another new take.
(*Waid and Yu’s version in Birthright was very good, but that was 15 years ago now - and even the Johns/Frank Secret Origin one is almost ten years old. Morrison’s new take in the New 52 didn’t completely work for me, and neither did JMS’ Earth One version. I like Superman For All Seasons a lot, which has lots of origin elements, but that’s 20 years old now, so it’s probably stretching the definition of modern. All-Star Superman is great for what it is, but the origin is just one four-panel page. There’s a lot more to unpack there.)