If we are going to make breaking changes in this release it may be wise to also do any package renaming in this release to keep the disruption limited to a single release instead of multiple.
Specifically, I propose we take this release to do all package renaming to clarify the difference between classes that are "internal" to Log4j core and should not be depended on, and packages that we intend to export when Log4j core becomes a Java 9 module. This likely means introducing new "internal" packages and moving classes and interfaces into these new packages. I believe this is in line with what Matt proposed a while ago as the plugin API for core. All classes and interfaces that are not in an "internal" package are safe to depend on and we commit to preserving binary compatibility for such packages. Everything in a package with "internal" in the name is subject to change. Should we aim to complete this work before the 2.11 release?