The 'Fusion' section at the end is interesting. macOS 10.13 didn't convert Fusion drives to APFS, but 10.14 will. Presumably this specific support for Fusion drives is new in 10.14.

HFS+ had no knowledge about Fusion drives, the caching was handled entirely at block-level by the lower CoreStorage layer (although later versions did add some flags so CoreStorage could pin metadata/swap blocks to the SSD).

Now what I'm really interested to see is if they open-source the filesystem driver along with the macOS 10.14 code drop. HFS+ (and its utilities) has always been open-source, last year APFS was not.