For now, this theme is used mainly for testing limitation of the e107 core with Bootstrap 4. If there is something wrong, we need to know.
Together with this theme are core bootstrap4 and new theme developed. All for 2.2.1 with some workarounds. Any update of this theme will fix some things or add new functionality.
There are a lot of new features for theme developing already in Github version of the core. And new ones are coming. They are so big and so "life-changing" that after release new stable version there will be Freelancer version 5.
After this, there are plans for a new theme based on this because with sass version it's really easy to make new ones. Or extend theme preferences.
Everything depends on feedback and user support.