Future of Group Content
All they mean is that the story of Arkk is done. New fractals with deal with new storylines but they will continue to be added.
They are still gonna keep adding Fractals, at the very least until we have a single unique one for each tier. Who knows after that they might change the system again or add 101, 102, etc. But be sure that the Fractals team still remains a team and will keep adding content.