Java 9 introduces the Cleaner and Cleanable utility classes which take care of wiring up phantom references to a queue and a cleaning thread draining that queue.
While this lets you separate out the witness that will perform a post-mortem cleanup after the owning object has died, all the caveats about GC-triggered resource management still apply, i.e. it is still preferable to rely on AutoClosable and try-with-resources blocks to manage the lifecycle of resources, not on the garbage collector.