I remember quite some time ago reading somewhere a proposed structure for collections that included a tasks folder, along with playbooks, roles, etc. Is support for tasks in collections still planned, so that they can be loaded with include_tasks: my.namespace.task_file?
No, not tasks directly, but playbooks
https://docs.ansible.com/ansible/devel/user_guide/collections_using.html#using-a-playbook-from-a-collection