If there is one thing most of us probably would like to see is a custom boss track to fit each boss, as for shadow bosses having an echoed darker remix of the normal versions track. Vanaduke should keep the old track while Snarbolax should get something similar to the "Claws of Nature" melody same with Roarmulus twins and "Mettle of a Gremlin" and Royal jelly with the new lichenous lair music. I for one get tired of listening to the same old track while knowing there's an opportunity to make boss experiences a lot better.
See this thread and this sample music from that thread.