Again, how is he "slumping pretty badly right now"? He has gone 2 SM-Liiga games without a point, and before that was on a 4 game point streak, not exactly a bad slump. I'm guessing you think "not many posts about Barkov recently, he must be slumping!" In reality Tappara have played just 2 SM-Liiga games over the past 11 days, pretty hard to score when your team isn't playing.
With that being said, I certainly won't be surprised if Barkov drops below a point per game as the season progresses. He just turned 17 in September, he's playing in one of the better pro men's leagues in the world, and he's the top offensive threat on his team, so the opposition will focus heavily on shutting him down.
What I don't get is why you think him falling below 1 PPG would kill his draft stock. He's got outstanding hockey IQ, he's big and strong, he plays at a high level offensively and defensively, those are the things that scouts care about. I'm sure his production will be great at the end of the season too. Do you really think 1 PPG is poor production for a 17 year old in the SM-Liiga? Question for Finnish fans: has a 17 year old EVER hit 1+ PPG in the SM-Liiga? Mikael Granlund is the only one who comes to mind as being close to 1 PPG, and he was still a bit below. Many top Finnish prospects don't even make the SM-Liiga as a 17 year old, and the few who do generally do not produce much at all. Granlund is the only player I can think of who has been particularly close to 1 PPG recently in the SM-Liiga, all the other top drafted Fins were well below 1 PPG (Mikko Koivu, Tuomo Ruutu, Joel Armia, Joni Pitkanen, etc.), with many being closer to 0.1 PPG.