Thanks interesting read!
Some thoughts from a Perl perspective (which wasn't mentioned)
- companies could restrict their proprietary modules to the same top-namespace like Apple::
- build systems could refuse to install from such private namespaces
- examples like My:: or Our:: come into mind as private by default
- CPAN could deny releases into "private namespaces" or similar
- another option for privacy could be leading underscores package _CompanyModule;
Disclaimer: I didn't thoroughly check if any of this is already done. But I found at least one module released under My::Object