Perhaps Scott Walker and others are such strong advocates for less government because their own first hand experience suggests complete incompetence. That is all. http://www.huffingtonpost.com/mary-bottari/scott-walker-dumped-as-ch_b_7442782.html?ncid=txtlnkusaolp00000592
Not sure what they'll do with Mereen since there's no pending war and Selmy is already dead. Will Dany even fly off? She's not as torn as she was in the books. Tyrion rules in her absence? Just doesn't make sense to me. Maybe there's a Fruition in the out scene and she climbs aboard and tames him? Even that feels off.
A huge part if those books was Jaime and Brienne touring the Riverlands. They've also cut a lot of Dany's struggles and the Tyrion journey. Add in that Quentyn, Iron Islands and Aegon were all cut... a lot less to cover.
A few things are out of order but they'll end up mostly right where the books let off.
Actually, if thy saved it all for the end of the season... they could have Drogon return and Dany fly off, Un-Gregor get revealed plus Varys kills Kevan, Theon finally rescues Sansa while Brienne plays the role of the singers and dies saving them and then Jon gets stabbed at the wall. Not sure where they end the Dorne plot line other than maybe they save the Doran plot-reveal for the end and he sends the Sand Snakes off to cause a ruckus.
There's actually a bunch of stuff that they set up like the books but then as they've moved forward, they cut the second part of the storyline because they decided it was a time crunch. They probably planned to bring him back and still might.
Without spoiling anything, similar to how some other minor character was in Sansa's place in the books (posing as Arya), a different character was in Dorne instead of Jaime (doing different but similar things). Jaime did a bunch of other "being responsible" stuff in the books that would potentially be boring to show on TV... and in that storyline you at least hear of the Blackfish.