Partial Clone garbage collection?

[Simon Holmberg <simon.holmberg@avalanchestudios.se>]

I've been experimenting with the new Partial Clone feature, attempting
to use it to filter out the otherwise full history of the large binary
resources in our repos. It works really well on the initial clone. But
once you start jumping around in history a lot, the repo will grow out
of proportion again as promised pack files are fetched.

Are there any plans to add a --filter parameter to git gc as well,
that would be able to prune past history of objects and convert them
back into pack promises? Or am I wrong in assuming that this could
ever act as a native replacement for LFS? Without this, a repo would
only continue to grow ad infinitum, resulting in the same issues as
before unless you actively chose to delete your entire clone and
re-clone it from upstream once in a while.