I have a few years of experience with CakePHP 3.5+ within very large projects, and I searched for a solution to rescale the rather flat MVC structure of CakePHP.
I came up with a domain driven approach. It requires minimal refactoring, even for large scale apps.
Please have a look at it, try it, and let me know if this can be of any help to the community.
Agree with @MarceliSzpak, plugins are the better way of achieving the same thing. While not strictly DDD, take a look at the code of Croogo CMS, a complete CakePHP based CMS that uses multiple plugins to achieve separation of concerns.
Thanks for your input guys. Here is a link to the discussion I had on tha topic. It matches what you proposed. I like the final post on setting different template paths from ADmad.