The roadmap for Cloud Custodian is maintained at the org level at this board:
Custodian is an Open Source project primarily run on volunteer time, as such the Roadmap is aspirational and purposely not milestoned or guaranteed to be implemented within a certain amount of time.
We welcome contributions to these items, and also welcome community feedback as to what kind of features/fixes and priority of these features users would like to see.
If you want to help out check the contribution documentation, file issues and dive in!