The new root DNSKEY is in use since October 11th 2018. The old root DNSKEY is still present in the root zone, and will have the revoked bit set on January 11th, 2019. The intent is to monitor RFC8145 data from all the root-server operators.
The DNSKEY roll for the root is a major event. The most noticeable step was using the new DNSKEY, which started on October 11th. The next step is revoking the old key. This is a minor event, but should still be visible in our RFC8145 data. We will monitor this event and track what happens via various measurement techniques.