Could Propecia Make a Mature Hairline Back Into a Juvenile Hairline?

Theoretically, could Propecia revert a mature hairline back into a juvenile hairline in the non-balding male?

I do not believe so. I would say that the mature hairline develops as the hairs from the original juvenile hairline reach the end of their growth cycle (developing apoptosis). It’s like asking theoretically if you can turn back time.