Game of Thrones as a series seems to be paving the way for Daenerys Targaryan to seize control of the Seven Kingdoms and become the benevolent ruler worthy of...a proto-Democracy? “Break the wheel,” as she puts it. To do so she'll have to deal with the Lannisters and the raging Euron Greyjoy. She'll do it with the help of her army of Unsullied, a horde of Dothraki, and any surviving stragglers from House Tyrell.
Unfortunately, most of her a fleet of Greyjoys are caput after Euron's surprise attack, which also left the Dornish Sand Snakes dead. The threat of the White Walkers also forced her to pivot away from fighting Cersei to fight the Night King, which could come back to undercut her efforts. All this and she’s down a dragon after Jon Snow’s fruitful if ill-advised trek North.
Basically, Dany will need to use the power of her remaining two dragons to burn back The Night King's army of the dead when the undead leader campaigns south of The Wall. Considering everything that is involved with killing White Walkers, and wights' strong association with dragons (obsidian equals dragonglass, valyrian steel equals steel forged in the fire of dragons, fire equals... fire), if anyone is going to have the methods needed to defeat the dead, it’s probably Dany (even Cersei thinks so!). In her visions in the House of the Undying, she saw snow fall on the Iron Throne, but that might have just been a metaphor for the Night King’s attack coming to King’s Landing. There, Dany can hold the city and protect the people (instead of the last time a Targaryen - The Mad King - tried to hold King’s Landing) and claim the Throne, with the future of Westeros at her fingertips.