He could step in next year and play in the top-six. He's not quite MacKinnon level but he's pretty darn close.
However, there'd be nothing wrong with putting him on the 3rd line to start. Gives him time to adjust and if he doesn't need the adjustment period then he solves one of our biggest needs: scoring depth up front.
The really exceptional part about Lafreniere is his attitude. He has that "I'll do whatever makes the team better" attitude. So as far as LW or RW, I'm sure they could try him on his off-wing and he'd give it his best effort. He has, however, played pretty much exclusively on the left. The biggest question there though is this: Can he play center? Usually guys come in as centers from junior and move to wing, but a few guys have gone the other way. I don't think a team would mess with that in his first couple seasons but I could see them trying it down the line.
Also, if by some miracle the Rangers win the lottery, I wouldn't expect Kravtsov to be in the organization too much longer. He'd immediately become a major trade chip to start addressing other needs. Same could possibly be said for Buchnevich.