The Fallen will die out first if we keep attacking them. The Splicers are not the Taken, they aren't replacements. Losing so many Splicers, SIVA, and their leader, Aksis, is a devastating if not fatal blow to the House of Devils. The House of Exile will never pose a significant threat. The House of Wolves may try once more, but as of right now they are a shattered house. Winter is nearly destroyed. Kings are the only ones that can make a comeback sufficient enough to cause a lot of damage. Then again, they might not go extinct, maybe Variks can bring them all to their senses. The Hive lost one god, but they still have Xivu Arath, Savathun, the Worm Gods, and the Darkness itself. Xivu Arath is based on war, Savathun was based on manipulation, and Oryx was initially based on understanding. We have another Cabal fleet in the form of Hive or an army of Witches. If we get passed them, who knows what the Worm Gods can do? The Cabal here will always be defeated, but it is unknown how many soldiers they have. Until the Emperor and the remaining chain of command is destroyed, the Cabal will always exist. The Taken under Oryx's control are slowly regaining their original conscious. Noru'usk of all Taken has shown this. It is unknown if they are completely exterminated or if between the year gap (lore-wise) of TTK and ROI they reverted back to their old selves. I don't think Taken can reverse physical forms, but they have been shown to reverse mentally. Unless the Worm Gods directly assume power over these Taken or Savathun or Xivu Arath has figured out how to Taken Queen, then these Taken are out of Hive hands... unless they were Hive before. Vex... Vex have been proven to die. Vex, however, can manipulate space-time. The Vex won't die out without the destruction of the Collective Mind, which is still unknown whether it is an actual collective of Vex Minds or a single Overmind. The Vault of Glass is out of Fallen and Hive hands, which means the Vex can start rebuilding their Time factory known as the Vault. The Vex as of the end of RoI's main story are the most powerful beings in the Sol System besides Guardians, so who knows what they will/can do by Destiny 2?