What is your current rclone version (output from rclone version)?

rclone v1.47.0
- os/arch: linux/amd64
- go version: go1.12.4

What problem are you are trying to solve?

Serve S3 protocol for backends that don't support it

How do you think rclone should be changed to solve that?

Let rclone via the serve parameter act as an "s3 proxy". Currently rclone supports many backends which lacks this, while many other tools commonly implements S3 as a backend. Something like https://github.com/minio/minio coupled with rclone backend's would be very cool. Yes I could do it with fuse+minio, however that would add another tool and complexity.