8 new Rebbes were just crowned

The Viznitz-Monsey Rabbi has 8 sons and sons-in-laws who all on his death have become Rebbes. It is very hard for me to believe that all 8 are worthy to be Rebbes and it is sad that because of an accident of birth they are becoming Rebbes. I never understood this whole idea of inheriting the leadership, throughout history we have seen that many/most times sons of great men are not great. In fact this is an explicit gemara. The gemara in נדרים פ"א states the following:

הזהרו בבני עניים שמהם תצא תורה ... ומפני מה אין מצויין ת"ח לצאת ת"ח מבניהן אמר ר יוסף שלא יאמרו תורה ירושה הוא אצלם ר ששת בריה דר אידי אומר כדי שלא יתגדרו על הציבור.
Be careful with the children of the poor because from them will come the talmidei chachamim ... R' Yosef said why is it that talmidei chachamim's son's are rarely talmidei chachamim? So that people will not say that Torah is an inheritance. R' Sheshes the son of R' Idi said so that they will not become haughty and imperious over the people (because they and their ancestors were Talmidei Chachamim).

We see from the gemara that Torah is not an inheritance and being the son of a talmid chacham not only doesn't guarantee that you will be one, but in fact the Gemara states that he probably will not be one.