Few things, as much as I don't really like the Legwand deal, Holland generally doesn't give up prospects who go elsewhere and succeed past his expectations. Look at Shawn Matthias, people were livid that he was traded, he hasn't amounted to anything. Same thing with Mursak, Ritola etc... The one that people hated the most was Quincey and they hate him even more now that he's back. I'm not defending Holland, I'm just pointing out that I don't see him really screwing up on the evaluation of the prospects in terms of trade value.
So, to answer the question at hand, in a system like Nashville's and the fact that they haven't generated any real forward talent outside of depth players, I think Jarnkrok will be a 2nd to 3rd line player getting no more than 55 points at his peak. More likely, he's a 35 point player who gets traded at some point or goes back to Sweden.