You could noticeably see his confidence continue to grow throughout the season, which he capped up off with a great Clark Cup performance. Chicago has been an absolute powerhouse these past 2 seasons and it can't be long before an NHL team hires Ryan Hardy to groom as their next GM.
Fantilli isn't ready for NCAA hockey, but it has no bearing on his status as a high-end prospect. I wouldn't rule out a return to the Steel next season. The team is going to lose most of its stars (i.e. Coronato, Farrell, Samoskevich, Doan, Middendorf, etc.), so Adam would be the premier guy on the team next year, and it'd be great for his development to carry the load for the team. They'll also return Ufko and Blake, and Adam's brother Luca would benefit from another year in the USHL before joining Michigan, too. If Adam really wants to play NCAA hockey with his brother, the path is pretty obvious to continue playing together without disruption.
And if Hardy is still with the Steel next season, there's no reason to believe they won't retool once again.