What a great Summer to have cap space and be rebuilding. Cap is not going up and lots of teams with little to no room. There are a LOT of contracts in the 4-6 per range that teams need, want, or at the very least would not mind moving.
Van, Tampa, , Calgary, Wild, Vegas, Kings, Blues, Isles, Oilers, Caps, Stars, Leafs, Flyers, Rangers, Avs, Bruins, Winnipeg or more than half the league are going to struggle to fill out their roster or outright MUST do something to get a compliant roster. Especially if you look at what is the likely price to keep their RFA's in the fold.
Florida, Montreal, San Jose, Pittsburgh, Seattle & Ottawa are teams I would put in the unlikely to be buying a significant cap dump, but they probably could squeeze one in.
That leaves Arizona (which until the stadium gets resolved they are not taking any actual salary playing in front of 4600 fans...so LTIR contracts and maybe a contract like Myers after his bonus is the only cap they likely will be eating), Anaheim, NJ, Wings, Carolina, Columbus, Nashville, Buffalo. Buffalo has a lot to deal with next Summer with it's own players so they are likely out for any deal more than a year. NJ & Anaheim may not be overly interested (or have much room) once they deal with the 4 or 5 RFA's they need to resolve.
Debrincat will knock someone out of the cap buying market. If Ottawa does not trade him and qualifies or extends him, they are for sure out. If they trade him, the acquiring team is likely out. I suspect he ends up being moved to Detroit for not a huge haul and signs an extension there.
There really are about a single handful of teams that can take a 4-6 million dump without having to give cap back and the Hawks have 5 or 6 spots.