It’s here! 4.0.1 is now released.
This essential release is primarily focused on NSX-T 3.0 support with Cloud Director 10.1.1, so all cloud provider partners who have been planning their upgrades and want to keep their DR-as-a-Service running now can. This release also includes several resolved issues and updates of third-party libraries that provide security fixes.
VMware Cloud Director Availability 4.0.1 supports an in-place upgrade from VMware Cloud Director Availability 4.0, 126.96.36.199, or 188.8.131.52. To find out how to upgrade from 3.x, please see the release notes here
Please find the download locations for this update here (needs my.vmware account):