The thing is I'm not expecting them to all make the roster at once.
Nylander and Leivo most likely get looks after the TDL when we need bodies. Similar situation with Percy or Harrington assuming we move a defenseman.
Its unlikely we would have that roster at the start of next season but around December/January I wouldn't be surprised if we had 4-5 sophomore/rookie players around the roster. Remember Leivo and Percy already have NHL experience, same with Morin and Harrington.
Johnson is tearing it up, could see him getting some reps in the AHL before making the team next year. Zeitsev is definitely NHL ready and probably in a top 4 role if we can land him, but many teams seem interested.
I fully expect some of the prospect depth to be packaged up and we take advantage of our cap space.
Take a team like the Ducks for example who have an internal budget and have no significant contracts coming off the books.
Next season they've got the following happening though:
Kesler goes from 5 to 6.875
Despres goes from 900K to 3.7
Anderson needs a sizable new contract off his 1.15 cap hit
Vatanen needs a sizable new contract off his current 1.26 cap hit
Lindholm needs a sizable new contract off his current 894K
The Ducks are only 1 example of a team that will have to shed salary by dealing out valuable pieces likely for cheap pieces (and cheap youngsters specifically being coveted).
Tampa if they extend Stamkos still have to deal with Kucherov + Killorn raises and will have to shed a lot of dollars.
Calgary is near the cap this year and next year have the Gio extension kick in + have to give huge pay increases to Guardeau + Monahan.