Arjuna brings his chain of reasoning to a close. These faults of those who destroy the family, he says — faults that cause the breakdown of social order — wipe out the age-old traditions of both community and family.
Picture an ancient tree whose roots are cut. The branches dry out on their own. In the same way, when the foundation of the family is destroyed, everything built on top of it — the way festivals are celebrated, the way elders are honoured, the way puja is done, the way children are raised — all of it withers.
Arjuna uses the word 'shashvata' here — eternal, timeless. These were traditions meant to endure forever, passed carefully from one generation to the next. And yet even they will be swept away. The depth of Arjuna's grief shows in this word: he is mourning not just lives, but an entire way of life.