One detail I saw pointed out in a meme: with the destruction of the Sept of Baelor, all the leaders of the great houses at the beginning of the series are now dead.
In order of demise:
Jon Arryn, poisoned by the wife
Robert Baratheon, murdered by a pig
Ned Stark, beheaded for "treason"
Tywin Lannister, Elvis death
Balon Greyjoy, thrown off a bridge
Doran Martell, kiled in a coup
Mace Tyrell, nuclear victim