In the recent posts titled "We need more keywords, captain!" on the OpenJDK amber-spec-experts mailing list, Brian Goetz "proposes a possible move that will buy us some breathing room in the perpetual problem where the keyword-management tail wags the programming-model dog." His proposal is to "allow _hyphenated_ keywords where one or more of the terms are already keywords or reserved identifiers."
Goetz points out in the original post that Section 3.9 ("Keywords") of the Java Language Specification spells out the current keywords in Java and that these chosen keywords have been stable since Java's inception with the only changes being the addition of the *highlighted* keywords shown below (assert in JDK 1.4, enum in JDK 1.5 and _ in JDK 1.9):