Hi,
The aim of this project is making it easier to create bigger test libraries. Instead of having all keywords in same class or module, you can split them to multiple classes/modules. A good example of this is the SeleniumLibrary. It uses the DynamicCore, not HybridCore, because it makes it easier to run a custom action if a keyword fails.
The whole PythonLibCore project was actually created to enhance SeleniumLibrary architecture. Unfortunately it hasn't yet been documented adequately and due to me being busy with Robot Framework 3.2 and then 3.3, I don't know when I'd have time for it. If there are others interested to help maintaining the project, let me know!