Thanks for your reply! To be sure, the Electronics workflow in Fusion does not depend at all on the Managed Libraries system in desktop EAGLE however Managed Libraries are there for existing EAGLE users still coming up to speed with Fusion to maintain their existing workflow and if need be, still use the Fusion Sync capability in EAGLE to interact with Fusion, especially when servicing legacy designs where migrating them to Fusion may not make sense.

The whole of this new electronics experience is based on cloud storage, cloud versions, sharing, collaboration and everything you've come to expect with Fusion. EAGLE had a legacy of desktop libraries being stored locally so there's a path for loading these into Fusion as well and as they are loaded, they will take on versions in Fusion Team and be stored alongside any other content you have.
In fact, opening a file in the browser will display in Fusion Team and the same redlining, markup, callouts, etc are all available, launching from the data panel.

We do not want to encourage non-versioned, non-managed data as that breaks some very important workflows for users who have come to depend on their data being wherever, whenever. I think what Edwin was a bit unclear on was whether the libraries in question were EAGLE's Managed Libraries or the new Electronics Library in Fusion. The Libraries in Fusion are fully supported by Fusion and the Managed Libraries are the previous incarnation of this from Desktop EAGLE. Both will work but Fusion will promote the use of Fusion Team, the Data Panel, and the cloud storage / portability / etc behind Fusion 360.
I hope that helps address the confusion!
Best regards
Matt Berggren
Director - Fusion Electronics, EAGLE, Fusion 360 Platform
Autodesk