It seemed likely as one of the producers spoke about a rough target of seven seasons for the entire series. WOW and the last book could end up requiring an extra season, but just the fact they're currently envisioning seven seasons as a possibility pretty much means they're of a mind to condense the material from AFFC and ADWD into a season and a half. The way they restructured/divided ASOS will let them move forward in the North, and with Bran etc. and with Dany and LF/Sansa while spending a few episodes to conclude the rest before they launch into their AFFC or ADWD arcs too.
They have roughly 30% of ASOS or less left to cover, but some of it involves the sort of minor players/complexities they've so far often simplified or even cut (what I think is that they moved the KL ASOS ending to s4 not to have both big events in the finale of s3. They decided to open s4 with the second instead.)
As for AFFC/ADWD, when adapting them I suspect they'll focus on the arcs involving the established characters and all that's required to lead into WoW events and the ending of the series (about which they know a whole lot more than us), and simplify and cut drastically in what's left.
I suspect the arc set in Dorne will be much simplified or not even included, they'll wait for whatever some of these characters do in WOW to make them appear, or give them much shorter introductions earlier.
GRRM had to remove a planned 5-year gap and build novels out of his material while not getting too far into what he wanted to keep for WOW, so he needed to detach material from this part that could be expanded to become sort of "prequels" to WoW (the Arya, Jon, Sam and Theon, Sansa chapters all felt quite a bit like that...) and invent new subplots and detours, and flesh out what was to be told in flash backs (parts of Tyrion's travels, possibly). He managed it with mixed results. The TV show don't need to follow him in that "trap" as they had this massive luxury of being able to re arrange and restructure things as early as ASOS. Had GRRM foreseen his structural problem earlier, he would no doubt have done something similar, and manage in turn to write AFFC/ADWD as one, more condensed novel.
He's a great ruthless and "cold bastard" type of "villain", with good, believable motivations. I wouldn't say "sympathetic", but he's a great character the audience love to hate. No doubt his death will cause some shock, after the death of Joffrey that removes another antagonist. But they're already at work setting up others... Ramsay is already more iconic than in the books, and it will be time soon for Cersei to step up and really shine as the main "villain" who turns into a victim, and I've no doubt the actress will pull it off, especially facing Natalie Dormer as Margery. With those two actresses it will be great replacement for the loss of Tywin and Joffrey in the series, with the Boltons in the North. I expect Margery vs. Cersei will be in full swing by the end of season 4, with season 5 in KL focused more on Cersei's downfall. This makes me expect the royal wedding to take the core of s4 ep 1-2, and then as the focus shift more to Dany and Jon in ep. 3-4, the fall out of the wedding might be stretched until mid season, with Tyrion's escape and Tywin's death. That would leave time for things to move into Cersei vs. the Tyrells territory for the end of s4.