I don't think she is power-hungry, I think she is an entitled brat. No doubt, Viserys raising her and filling her head with his non-sense played a role in that. But she believes that the Iron Throne is hers by right. I don't think that is power-hungry.
There are so many different ways this season could have gone, I feel like the show-runners really missed an opportunity to tell a good story. My hope was that it was going to go like this:
Deal with the Iron Throne last season in which Dany attacks Kings Landing immediately. Cersei sets up Wildfire throughout the city and is ready to kill all the people and destroy KL, Jaime realizes she is crazy and has flashbacks to Aerys, strangles her to save the population and city. Dany shows mercy to Jaime and establishes her rule and re-appoints new lords throughout the broken kingdom.
In the North, WW and allies are attacking the wall. Because of his mark on Bran, the NK is able to cross the Wall. The horn that Sam found is still at the Wall around Ed's neck. NK gets the horn, blows it and the Wall comes down, end of season.
Season 8, is the war against the Long Night, Winter has Come. Humanity gets pushed back and is slaughtered by the NKs forces. Dany and Jon unite the realm, Bran does some magicy crap, and the battles play out...ending in sacrifice and hardship...life, death, struggle.