Just recently I finished reading ADWD and simply loved it. It got me thinking about probable end games for SOIAF and the mind truly boggles at the posibilities:). The characters can be divided into three tiers based on their importance:

Tier I
Dany, John, Aegon, Stannis, Arya, Bran, Tyrion, Cersei, Sansa, Jamie

Tier 2
Tyrells, Dornes, Barristian Selmy, Melissandre, Littlefinger, Varys, Blackfish, Griff, Stoneheart, Rickon, Asha, Theon, Victarion, Brienne, Davos

Tier3
Faith, Easterosi (Mereneese, Yunkai...), Wildlings, Other ironborns

Little knowns (as of date):
Others, Rhilor, PTWP, Artifacts such as swords, horns etc.

I have purposefully not mentioned boltons & freys as the days for the Lannister_Bolton_Frey axis of evil seem to be numbered which seems to be a bit confusing as who will be the baddies in WOW & DOS? Only the Other?

It seems that Aegon, Jon and Dany will be the 3 leads going forward. Each of the three leads will be supported by a character that is politically savvy (Like a Hand. Note that all three are known to lack cunning) and a character who has strength either through magic or loyalty of others.

Let me start with Jon. Assuming that J = R + L and that Jon is still alive, I feel that Jon will turn out to be azor ahai. I think he will be supported by Asha and Bran. Jon will get Stannis's lightbringer assuming Ramsay's letter is true and Stannis is dead. Melissandre will probably sacrifice herself to bring back Jon. Queen selyse and her men will eventually support Jon. Jon will crush Boltons and win loyalty of northeners. Theon will probably be sacrificed to old golds or fire god. Davos and Rickon will probably hold north with support from other northeners.
Chief Foe : Boltons, Others

Aegon: Aegon is most likely the PTWP and has the strongest claim to IT. I somehow feel that he will wed Sansa and Blackfish Tully will have a part to play. Sansa is already wed to Tyrion but since they never slept together its ok :). He has a strong and disciplined army but will most likely loose Connington who will be replaced by Blackfish Tully. He will probably acquire Dawn. He seems bit ill equipped on magical side but may be Thoros can fill that spot for him. He will kill Jamie and Loras and become a true champion.
Cheif Foe : Remaining Lannisters, Tyrells, Freys, Stoneheart(?)

Dany : She has dragons but no way to control them unless she can get the horn from Victarion. She will be most likely supported by Tyrion and Selmy and will have a strong army of Dothrakis, Unsullied (those that survive the battle) and other Eastrosis. And of course the Dragons. I am thinking that one or more dragons will be killed by faceless men.
Chief Foe : Slave masters, Qarths, The other, FM?

Arya, Littlefinger and Varys are all the dark horses and its impossible to tell which way they will go.

Let me know if you agree or disagree or have other theories?