would a prequel with the replicants

Not particularly. We see them at a crucial moment when they attain emotions and become human.
I suppose you can show the road that led to that moment but it wouldn't be dramatic and would cheapen the original movie. Besides we live in the age when it all will be about the oppressed and we'd just have another Westworld.

You know what?
I like that idea. I think it would be really good