I certainly agree with you, that pretty much each project needs re-rendering, for many reasons (e.g., ...client changes his mind). To wait each time for the distribution (again—as your initial post describes it) is certainly doable, but not nice. Especially not nice with a tough deadline close to you.
I have of course no idea what the developers will do in any future release ;o) as you mentioned “hope we got this on R16”. Nor do I have the option to talk about anything that is not released.
What I can do, is to ask you how this would work and kept simple. Simple is here the target as everyone has different things to do in a demanding project, than to clean up temp files. Which might cause problems after a while, if not cleaned up. Double versions of the temp content, or shared versions which vanish if the clean up is not done carefully. As most of us have no rendering - assistance/engineer, such as big studios have, we need to keep it simple.
My idea would be to name a job ticket with each rendering. Those job tickets are like reports and if the job is done they can be used to identify the material distributed and delete it. With such tickets the Render-Job-ticket manager (“Ticket-Man” ;o) can check if there are shared objects with other job-tickets and exclude those from the cleaning-job. The job ticket could also contain which frame was rendered when and where, to reflect Ryan’s request). Sound like a reverse texture manager function…
Would that work for you?
Perhaps you might suggest that to MAXON.
All the best
Sassi