There will be multiple teams who will want to trade for Roy. This is one of those rare situations where you can acquire a good core player where the team would keep them if they could but can't, due to cap (mismanagement).
It's kind of like how LA got Willie Mitchell and Rob Scuderi and we all know how that turned out.
Except, on top of that, this is a top RHsD, not some winger. For example, I could easily see him in Ottawa playing on the other side of Chabot on the top pairing. That could stabilize the entire D corps.