Cavani won't leave,
Lacazette is not a clear improvement on Higuain or any form of improvement, they already have a small fast striker in Dybala who starts for them so Lacazette is surplus. Juventus play a small striker alongside a big striker usually and Lacazette doesn't help in that regard. They have Dybala and Vadala for that pacey small striker role.
Lukaku could go but again that's paying for potential. None of them are better than Higuain at this moment in time.