I am well behind you guys, and this may seem too simplistic an idea to even entertain, or it's too obvious, but is there a way for the end game to not involve widescale massacre and toppling of all existing power struggles?

For example, it seems utterly impossible for a Baratheon (Lannister) line involving Cersei's children and Dany to co-exist. The Tyrells and Lannisters are a political marriage that can't last.

Basically, it's hard to see the Lannisters winning without wiping out several factions wholesale. Maybe the lolGreyjoys win some sort of greater autonomy, or a (Littlefinger)-Stark restoration in the North could happen (where does that leave the Boltons though?).

But with JKDS mentioning the flaws in some major characters, and with the Stannis faction doing the "protector of the Realm" bit and joining with Mance, there are clear implications that uneasy alliances and compromise will have to be made to face external threats (undead, Dany).

Another obvious alliance is some sort of Jon Snow-Dany joining. There's some possibility of a Dany reaching accord with a decimated, Cersei-less Lannister group, via Barristan and Jamie.

Really though, if you see these as the major players:
Targaryens
Lannisters
Tyrells
Starks
Baratheons
Wildlings
Littlefinger

It seems like most of them need to be wiped out. This doesn't account for Arya, who's not furthering Stark causes, or a few other pretenders (Boltons, Greyjoys).