Maybe it is just me, but I don't see the situation as being so dire. This adversity will be helpful in figuring out exactly who stays and who goes - and I already see a few players that can go. Before next season, the Isles probably need to make about five moves to revamp the team.
The first move is that the Isles absolutely must bring Sorokin over. As we have seen with other young goalies, they stabilize a team. When you don't give up back-breaking goals (that should be saved) and you trust your goalie, the rest of the team plays looser and better. Plus, Sorokin seems to have a great personality for the locker room and NYC market, as someone who likes to joke around off-ice, but is deadly serious on the ice.
Get the defense healthy and add CHEAP veteran depth (second move). I would be looking to bring back Green (or a comparable UFA) on a one-year deal for about $2-2.5 million. Assuming Pelech returns to form, which will be huge, and Dobson is gaining important experience right now, the Isles should be able to ice a top-5 defense corps. The four core defensemen should be: Pelech, Pulock, Toews (probably extended a year or two at $2.5 million AAV) and Dobson (with perhaps Wilde down the line joining this group if he isn't traded to help elsewhere). Add in Boychuk and Greene for sure (see Leddy and Mayfield discussed below) and that gives the Isles six quality defensemen at the NHL level with probably Hickey, Aho and Wilde in the AHL for depth (unless more is added by trade). Not ideal but few teams have much depth on defense now.
Third move, option 1: The Isles have to go all-in on an UFA goal scorer like Taylor Hall (doubtful to sign with the NYI), Hoffman or Dadonov. Hoffman would be my target and I do whatever is reasonably necessary to bring him in to play alongside Barzal. Dadonov would be the next choice. If you can sign a player like Hoffman or Dadonov, I trade Bailey for futures (to help restock the system or use in trade down the line) and see if I can move Leddy in a trade for a cheaper, albeit lesser defenseman to help the depth. Like the Trouba for Pionk deal in reverse. If you can't find that, get the best package of futures available for use later.
Third move option 2: If the Isles cannot add a goal scorer in free agency, then they are going to have to trade for one and I would use Mayfield and his cheap contract as one asset to do that. The other assets are probably some mix of Wahlstrom, Bellows, Holmstrom, Wilde, the 2021 draft pick, etc. In the right deal for a significant upgrade, Beauvillier is also on the table. I look to see if a trade built around Mayfield, Beauvillier and another couple assets can get a player like a Nylander or Rakell. What the Isles give up depends on the quality of player being returned.
For the fourth move, I revisit the Parise-Ladd swap. Try to find a workable deal there. I am not sure what it is going to be but, if you can move out Ladd's deal for a serviceable player and take on more real $$$ but work under the cap, you have to do it. Otherwise Ladd goes to Robidas Island and gets paid to stay away next season.
Finally, I let Martin, Brassard and Kuhnhackl all walk and I look to add 2-3 NHL/AHL tweener players at forward to come in and compete but also provide depth in the AHL. Ross takes Martin's spot and MDC is not guaranteed a spot unless he earns it.
Assuming the NHL salary cap moves up to the $86-88 million mark, the Isles should be able to resign their RFAs, although there might have to be a bridge deals for Towes and Barzal right now, add one top goal scorer and look to round out the team. Provided they make the tough calls on players like Bailey and Leddy (good players but redundnat to the Isles) and jettison Ladd. And a bit further down the line, contracts like Boychuk and Clutter will either come to an end in a couple seasons or be moved off the books via trade or buyout.
Of course if the Isles miss the playoffs, let's pray for a (long overdue) NHL draft lottery win, because that would expedite improvement, just like it has helped Carolina, Philly, the Rags, etc.