Hi @Stuart Wepener ,
Most of the Blueprint resourcing is going towards Template Specs (video overview) and Deployment Stacks, which is what Blueprints are eventually going to use under the covers. For authoring improvements, focus is bicep. The GA (General Availability) ETA is set for March/April when the new underlying resource types (template specs and deployment stacks) are ready and we can migrate everything over.
More info in this talk:
Most of the Blueprint UserVoice asks are either already implemented in Templates/Template Specs, or they are something we will address with above mentioned future improvements to templates/bicep and stacks.
Lastly, even though the Blueprint service is listed as “Preview”, we treat the service as GA, which means even once a migration path is made available, we will continue to support the current Blueprint APIs for 1-3 years or until everyone has been migrated.