Eh, D&D dropping Aegon made the show easier to adapt, but made the story a far worse experience. Same with the Ironborns and the Martells. The show has survived on spectacle for since Season 5, and while they can introduce well-written portions (Winds of Winter, The Door, Hardhome). Having Brienne actually kill Stannis, and Sansa move in with Ramsay was in-theory a clever way of condensing characters. However, their translation from paper to the small screen has not always worked well from a plot/character point of view.
There are still two books, possibly three left. The first three are known as act one, with feast/dance being act 2, and winds/dream being act 3. It would be worse storytelling if they were introduced in Winds of Winter. Feast even states that an uneasy alliance has opened up within the seven kingdoms, clearly putting a pause on most major plots. The plot then gets rolling again with Jon dying, Dany leaving, Cersei walking, Stannis marching, Aegon landing, Jamei and Brienne stonehearting....and everyone going to Meereen.