I think the defense is pretty easy to sort out, as we probably don't have to worry about Perfetti's long-term extension kicking in just yet. The only crucial piece we need to keep is DeMelo, and we should have the cap space to overpay him if needed. The rest of the RFAs and UFAs are pretty much inconsequential and can all be let go / replaced by other options. Might want to keep Heinola around, if he's open to giving the org another go, but the rest aren't needed.
What happens if DeMelo wants to explore other options, I don't know. It'll probably include a metric f***ton of pain, because that right side is terrible without him.