Joomla 3.9.0 was released yesterday. IMHO this version is a big step forward for all who want to stay GDPR compliant. I will soon publish a jOpenSim privacy plugin working with these new features.
But currently be warned: while the update via Joomla's built in updater works fine (at least from 3.8.13), the manual update file currently fails completely. You will end up with a file system from Joomla 3.9.0 with a database schema from 3.8.13 ... the usual database fix doesnt really fix at the moment
I expect 3.9.1 quite soon to fix this, but neverless are very happy, Joomla 3.9.0 is finally out and if you are updating via Joomla's built in updater, you should be safe (did I already mention that backups are always a good idea?).
Greetz
FoTo50