The BHG Core, ill-equipped to deal with the insidiousness of the nomads and their technology, ends up hopelessly infested. They then use their huge warfleet, larger than any single House (apparently), to take over Sirius and once and for all rid the nomads of the human plague.
Edit: Maybe the Order, along with the Houses, can stop them, but it seems unlikely. The Order is too busy fighting the actual nomads, and there's no convenient hypergate to open or nomad power supply to destroy this time.