I dont know about winning the cup, many teams have had the pieces but have never managed to win a cup.
I'm going to answer it differently.
To become legitimate contenders however, we need to improve our defense and add another top defenseman. Hughes could become our number one defenseman, we don't have anyone after that. Juolevi maybe, but he's a top 4, not top 2.
We've got great prospect depth at forward, and our strongest asset is our goaltending. At least one of Demko or DiPietro are going to be our #1 goaltender, my money on Demko.
As for center, all of that lies with Pettersson. If he can make the change to center (he has experience but hasn't played center in over a year), then center shouldn't be our main priority. Horvat and Gaudette are going to be excellent 2nd and 3rd line center man.
TLDR: at least 2 more years of drafting top 10, and we should have the pieces necessary to at the very least start making our way to becoming contenders. 1st line centerman (if Pettersson doesn't pan out at center) and another top 2 defenseman followed by consistent drafting.