Out of curiosity, how many minutes of gameplay did you watch of Kostin that was not a highlight reel? I have not seen near enough to make an adequate prediction about his progress. However, my spidey sense begins to tingle with such crazy predictions like yours that are given with such assurance. In my experience, anyone who talks up a late first pick AFTER the draft, but not much before the draft is mostly going off of hype and not actual eyes-on information. Less than a month ago we had a poll on who we would pick at 20. Lehterasenkshow did not pick Kostin who was available, but picked Poehlling instead. So I would guess your opinion on Klim has changed since then. Since he hasn't played a game in that time, it was either based on the prospect camp, which isn't a good indication of NHL readiness or on hype.
I picked Poehling based on need. We needed a good center, and I thought that Poehling would be the best available. I didn't imagine Kostin would make it past 15 realistically, but of course would drop due to a Russian-factor, his shoulder injury, and a WJAC that was lack-luster. I always thought he was going to be good, but of course after landing him (and a lot a couple of days before the draft) I started really seeking out more than just video.
I haven't watched a lot of games, but in talking with Russian posters on here, watching what clips that are available of Kostin's shifts, and reading about him from KHL fans, I feel confident enough to make a bold claim (and I do understand it is bold, so I guess take it with a grain of salt?). I felt that there was a lot of brake-pumping going on - too much so that I felt we were forgetting what I view as a real possibility. Pump brakes if you would like, and I will agree an opinion like that is more realistic. However I don't think it's as outrageous as some might think to believe that he has a chance to make a splash this year.
To be clear I don't mean to imply that Kostin is a first-year NHLer type of prospect. What I mean is that this is a perfect storm for Kostin: we've lost Perron, Jaskin can't stick on 3RW, Berglund is injured to start the season, we have been lacking speed, physicality, and scoring talent, and we have a coach that doens't require elite defensive awareness to play his system correctly (and allows for creativity and less defensive responsibility that would allow a player with Kostin's skill set to more easily make the team). Because I believe that Kostin's skill level is elite, it doesn't seem too far-fetched to me to say that he has the capability of making the team, and soon. What will he learn in the AHL more than he will learn in the NHL? He has all the tools, he has the drive, and he has the ability to play with bigger competition. Outside of adjusting to the ice, I suppose one could say that he needs to learn to use his teammates better, but again, I don't think you have to be in the AHL to learn that. I think if given a shot (and because of the perfect storm I think he will be given one) he will find a way to beat-out Jaskin for that 3RW spot. If he's the best player for that spot, then he will stick and learn to use his teammates and adjust to the faster pace in the NHL.
I don't even view bringing him up now as a risk. He's not a Yakupov - he's nowhere close to a one-trick pony. He has the work ethic, the confidence, and the size and speed to make him capable of making the jump in my estimation.
Will it happen? Perhaps no. I suppose this is like a Duchene situation where I see more possibility in others in that I think there is a path forward. We have the pieces to get it done, imo. But I don't know one way or the other if management will actually do that. The same is true with Kostin - I think he has the pieces to get it done, but I don't know if management will actually put him in the NHL if he looks ready during camp. I do know that the timing looks like it could be right, and you, me, and everyone we know (ostensibly including management) know that we need what Kostin brings. I think all of those things mean that Kostin could be in the NHL this year, and that it's not exactly crazy to think that management might feel the same way - even if they claim he isn't ready as of now. The combination of needing his skill-set, Jaskin sucking offensively, and having an open 3rd line spot and maybe an open 2RW spot if Schenn looks good at center means that they might be willing to overlook some of his immediate inefficiencies.