Let me share my thought. We have AEM 6.4 native install on windows 2012 using Java 8.0. Repository size is already touching 100 GB even after compacting and all optimization. The main contributor to this repo growth is Audit data and DAM Assets.
I'm thinking to move Asset disk storage to a separate disk space drive. just to minimize divide the size of the repository. FYI this AEM install can't use S3 storage l but our Datacenter and infrastructure have all the latest disk storage options to scale it.
Please share your thoughts and let me know if you have any questions.