If Barrie is traded and they walk from the rest of the UFA's there is a lot of work going into next season:
Forwards:
x - McDavid - Puljujarvi
x - Draisaitl - Yamamoto
Kahun(?) - x - Kassian(?)
x - Khaira(?) - Archibald
Haas(?), Turris(?)
I imagine they buy out Neal, might ride out the Turris contract, maybe see about re-signing Kahun and Khaira as RFAs. As long as Ennis stays consistent they probably offer him another 1 year deal and he likely takes it unless he gets a much better offer elsewhere (he wants to play for his hometown and if he has the choice would probably retire here).
Defence:
Nurse - x
x - Bouchard
Lagesson / Jones (whoever isn't selected by the Kraken) - Bear
Russell(?)
Goaltending:
??
Stalock?
Then you run into the issue of having too many 'new recruits' and waste a good chunk of the season trying to build chemistry. I don't see them letting all 3 major UFAs walk, to be honest. The only way I see it is if they trade Barrie or Nuge in hopes of finding a longer term replacement for one of those holes.
Edit: I didn't really consider rookies breaking in but I imagine they won't want a whole pile of them breaking in at once and they will likely look to sign proven guys for the main spots in case a rookie doesn't pan out.
Let's go with one forward rookie and one LD rookie make the team. Still lots of holes if they don't re-sign any of the major UFAs. I just don't see it.
Edit 2: Shit, forgot about Kassian...I guess he'll still be here.