I think the PEP is a nice step forward (I wish it were possible to fully automate the mapping of projects to import names though).
I have a question about the adoption of the PEP by existing projects. The PEP says that the pyproject.toml specification gains project.import-names and project.import-namespaces (by the way, the PEP uses project-names and project-namespaces at one point) and that tools can support calculating these dynamically. I am guessing they are optional new keys and the recommendation would be for tools to produce empty entries in the metadata when the keys are left out? Regarding empty entries, the PEP says
Projects MAY leave Import-Name and Import-Namespace empty. In that instance, tools SHOULD assume that the normalized project name when converted to an import name would be an entry in Import-Name
When build tools start supporting the new metadata format but projects have not updated pyproject.toml to include the new keys, wheels with empty entries will start being produced for which the import names might not match the project name (unless tools require the new keys but that would be more disruptive). Should tools really assume the project name and import name match in this case?