IMO the best chance Java has to close the gap on memory utilisation is Project Valhalla[1] which brings value types to the JVM, but the specifics will matter. If it requires backwards incompatible opt-in ceremony, the adoption in the Java ecosystem is going to be an uphill battle, so the wins will remain theoretical and be unrealised. If it is transparent, then it might reduce the memory pressure of Java applications overnight. Last I heard was that the project was ongoing, but production readiness remained far in the future. I hope they pull it off.

1: https://openjdk.org/projects/valhalla/