In terms of on ice play, Hanifin and Pronger at 19 were very similar. They were/are underwhelming for their draft position. But they're 19, when 98% of NHL defenseman are still in juniors or college.
I don't think he turns into a Chris Pronger, that's not his mold. His tools make him a threat to be a big Scott Neidermeyer. The question becomes does he have that type of elite hockey IQ to use them to their fullest advantage. A lot of high hockey IQ guys in the lower levels come up and we find out it's not quite the same at the NHL level, at NHL speeds. So far that's what Hanifin has looked like to me. And that shouldn't surprise anyone. Just because the rare player or two can do it at 18/19 doesn't mean others who will become elite someday will.
Hedman is the most obvious recent example. He really didn't look like much until his 21y/o season and then at 22 he really broke out.