A 9-game look is very different from a full season. I think it's too early for Crouse or Chychrun (or Strome, if I'm being honest) to play a full season in the NHL. A 9-game look won't ruin them, though. It's too early to fret.
Chychrun won't survive the return of three NHL caliber defensemen to the lineup, especially with DeAngelo pushing for time, too. Nine games in, I suspect someone from the AHL will be ready to swoop in for Crouse, too. Or perhaps a trade shakes things up now that the Coyotes have all that LTIR space to work with. Bragging about having so many promising rookies in the lineup without any need to jettison anyone could just be posturing to get full value out of whomever they intend to trade.
Something no one seems to be talking about—and something Chayka has mentioned a few times this summer—is culture. I wonder to what extent that's playing a role here, in both directions.
On one hand, this seems likely to be Doan's final year. I expect him to stick with the organization in some capacity or another, but perhaps they want these young guys to maximize their exposure to him as a player. Crouse especially has a lot to gain from paying very close attention to how Shane Doan was able to have such a long career.
On the other hand, young players bring an energy to the team. Youthful exuberance is a little infectious. They also prevent veterans from getting complacent if only so they don't lose their minutes. Those same vets can also establish a culture of mentorship, which will be crucially important moving forward. For example, Domi and Duclair have some vets to thank for how well they played last year, and I hope they will pay it forward and be integral to bringing the next crop of rookies on board. Next year, Dvorak and Strome can help Keller and MacInnis assimilate.
Chayka seems to be taking the long view overall (thus the hoarding of prospects and the phasing of those prospects' introduction to the league), and with how this franchise has struggled over the years, he is trying to turn a battleship around. There is more to fixing the team than just assembling a talented roster.