Six Kingdoms
Kingdom of Mountain and Vale - House Arryn
Ruler: Robyn Arryn; The Vale is a part of the six kingdoms
Kingdom of the Reach - Unknown
Ruler: Bronn; Highgarden is part of the six kingdoms; Bronn was given highgarden as payment of the Lannister debts.
Kingdom of the Stormlands - House Baratheon
Ruler: Gendry Baratheon; The Stormlands are a part of the six kingdoms
Principality of Dorne - Unknown
Prince of Dorne; Dorne is a part of the six kingdoms
Kingdom of the Rock - House Lannister
Ruler: Lord Tyrion Lannister; the Westerlands are a part of the six kingdoms; Tyrion is the hand of the king.
Kingdom of Isles and Rivers - House Tully
Ruler: Edmure Tully; The Riverlands are a part of the six kingdoms
Iron Islands - on/off part of Riverrun - House Greyjoy
Ruler: Yara Greyjoy; The Iron Islands have been a part of the Kingdom of Isles and Rivers on and off but mostly independent throughout history.
The North
Kingdom of the North - House Stark
Ruler: Sansa Stark; Independent kingdom of its own with almost all of the north pledging their allegiance to Winterfell
Other Major Houses
House Targaryen - Undecided with Jon out in the wild and the 7 kingdoms not yet knowing his true parentage.
House Tarly - Ruler: Samwell Tarly; Hornhill (The Reach) is sworn to Highgarden; from S8E6 voting scene, it's clear that Sam is in charge of Hornhill.
Extinct Houses
House Clegane,
House Tyrell,
House Martell,
House Bolton,
House Mormont,
House Karstark,
House Blackfyre,
House Umber,
House Frey