"Replace footage" with anything in the project (footage more abstract)

I would like to be able to “replace footage” with anything from within premiere thus having ‘footage be more abstract’. 
 

• Current Limitations: Replace footage only applies to footage on disk. 
• Improvements: Replace footage with anything already imported. It should just become a reference and behave similar to ‘replace with Clip from Bin’ but on a project level. I would like to be able to swap anything with anything within the project window: ie. Source footage with a sequence, subclip, AE project, imported image etc. and vice versa.
  
  A piece of ‘footage’ should become more abstract. Maybe all footage should get an additional ‘container’ with a basic timeline where you can manually drag in a new source and handle the duration etc. ‘Footage’ then can never be used in timelines directly only through the ‘containers’. Your edit is then totally independent from your source footage and you can swap the actual footage in the container and modify it if needed. This allows you to macro manage your whole project. You could put everything from ‘modify clip’ (interpret footage, etc) in this container. Basically how you deal with this reference throughout the project. 
• Usecases:
  - Footage within a Graphic (note: NOT graphic templates) cannot be swapped currently, thus one can only replace the source footage from a file on disk and NOT assign a different Clip/Subclip from the project, making native graphics not reusable unless you render all to disk and replace every clip (destructive workflow) and creates unnecessary bloat.
  - replace footage with a already imported image, video, sequence, project.
  - adjust your footage in a container before it gets used: scale to frame, crop, rotate, color manage,
  - grade on a project level at once, then overwrite / micro adjust in the timeline itself.
  - Video size is no longer a consideration when editing in a sequence.
  - you can fix footage before it is used (using AI).
• considerations:
  - self reference: possible parent child relationships that could cause a cycle.
  - option to pre-render sequences or subclips when swapping, keeping the link to the source and option to update from source (simular to offline footage).
  
  Thank you