I have already done first review of ContentDirectories
it is here: New Unity 6.6 ContentDirectory GOOD and BAD Q&A
my opinion is that addressables and assetBundles in current form dont deserve improvements. They deserves obsoletion and annihilation 
in favor of ContentDirectories
main question to ContentDirectories today is
how they meant to support
CDN packs
DLCs
Mods
Event Content Overrides
current foundation is pretty strong already