I managed to inadvertently update my VCSA for 6.5U1e to 6.5U2.
I was attempting to use the VCSA6.5U1g patch ISO to update my VCSA, apparently I wasn't looking closely enough, and the VCSA automagically applied the 6.5U2 update for me.
Is there a method to update the VCSA (embedded PSC, no linked mode yet) to 6.7 at this time, or do I need to wait patiently for the next available 6.7 patch release?
I'm afraid that you'll have to wait for a version that provides a supported upgrade path. Other than this you may consider to deploy a new VCSA, and migrate the hosts to it. This option however depends on the size of the environment and the features that you are using.
Btw. does your backup application (if applicable) already support v6.7?