There was some discussion about waiting for 6.0 in the pull request for 2.1.6, but they chose to ship this and instantly open a branch for 2.1.7 pull requests.
There are always kernel releases on the horizon, my experience has seen ZoL supporting them pretty quickly.
This concern doesn't make any sense. There are always new kernels on the horizon bydl definition, and there's nothing special about 6.0 at all. By this logic nothing should ever be released as it should always be waiting for the "on the horizon" kernel.