The way you suggest makes sense because that way you get rid of a lot of characters so you can be done with the actors as well. If they end the season like that, they can be done with Robb, Catelyn, various members of their entourage, Joffrey, and so on, and move on with new emphasis on other characters for subsequent seasons (all this of course presumes more seasons).

By the way, speaking of dividing the season differently from the books, I would imagine they are going to have to completely scrap the aFfC & DWD set-up. With Tyrion taking over as the fan favorite, they cannot go a whole season, or most of one, after his escape, without him, or without Jon & Dany. Then again, a lot of that last pair of books could be truncated, such as Arya's murder training, Jaime's ending the war peacefully, or Danerys holding court and vacillating about Mereenese customs and Daario.

I think a lot too is going to depend on how Jon Snow's maturation comes across (though the actors fit better for the characters as of GoT & CoK, I think the guy who plays Robb is more charismatic and better suited to the role Jon plays in SoS & DWD), and how well the actors playing Brienne & Asha/Yara can handle a portion of the story on their own, or as lead characters. Much of the Lannister Twins' story in aFfC is internal as well, and while I am confident of NCW & Headey's ability to handle what the roles demand, I can't help but wonder how it will translate on the screen. It may be that the excessive length of the later books will not need nearly as much screen time as the more action-oriented SoS. That is pretty packed compared to the other books:
Even prior to the king-killing weddings, you have Brienne & Jaime on the river, their fight & capture by the Brave Companions, Arya's adventures with the Brotherhood and then with the Hound, Catelyn dealing with Robb & their situation and of course, the RW. You have Daenerys in Astapor, and the fighting at Yunkai & Mereen, and Bran's journey with the Reeds, plus all the court intrigue with Davos, Melisande & Stannis and Tyrion & Sansa, which I just can't see them giving short-shrift to as Dinklage seems to have become the breakout star of the cast. Also, if they feel the need to keep Theon on-screen so the audience doesn't forget him, they might need to stick in the occasional scene in the Dreadfort's dungeons, which is all told in flashbacks in DWD. Hell, now that I look at it, I'm surprised they can cram so much of the book into one season.

But the arcs in the rest of the book make sense to be coupled with aFfC/DWD arcs, such as Tyrion's trial(s) & escape and journey eastward, or Sansa's flight and adventures with Petyr & Robin, or Arya's journey to Braavos after the Hound's wounding (and his subsequent religious undertaking). Jaime & Brienne's intertwined arcs from King's Landing to their reunion at Pennytree would also seem to make a good season-long story, as would Cersei's pro/per-secution of Tyrion as a prologue to her rampage culminating in her walk of shame. And the crossbow deaths of the Lannister brothers fit nicely in the same season, rather than eleven years apart.