Although it is still almost two months until feature freeze and rampdown, a number of features for Java 15 have already been announced. These include:
―Hidden Classes (JEP 371)
―Text Blocks (Standard) (JEP 378)
A standard version of two new garbage collectors also appears in the feature list:
―ZGC: A Scalable Low-Latency Garbage Collector (JEP 377)
―Shenandoah: A Low-Pause-Time Garbage Collector (JEP 379)
A second Preview or even a final (aka Standard) release of Records could be there. It also seems plausible that Sealed Types will also be targeted at Java 15 - as a Preview feature.