I've suggested we implement S3 compatible storage before, we'd need some sort of file handler to choose whether to do disk or S3 depending on the configuration.
I don't see how the ability to rename the uploads directory helps though. You can host it on network storage easily enough, it's not really dependant on the name.
I've done this a lot for WordPress, multiple EC2 instances behind a load balancer and wp-content gets mapped to EFS.