• Astoria has some technology to do this INSIDE their CCMS.
• Rudolfo Ryan may have some tooling here that has helped them with conref/keyref conversions for L10N.
• Perhaps the first step might be documenting best practices for how to do the conref-to-keyref conversion manually.
• It would be good to provide instruction/support for BOTH individual users doing a manual upgrade/conversion and vendors/CMSs doing an automated upgrade/conversion
• Possible TC issue: shouldn't the spec provide tooling/meta-scripts for these sorts of upgrade issues??

Eliot Kimber has a utility for this, a transform called "Make Keydefs" which can be found at: https://github.com/dita-community/dita-utilities.