I'll dig out my copy and refresh myself on it :) 

I agree with the bit about Snow having a change of heart, although I don't think it's going to be too drastic and I think that whatever is killing him, he would only agree to change if there was something in it for him, like medicine or maybe mercy? Coin would probably take the people that Katniss cared about, although she obviously didn't get Prim, Peeta and Gale. I can't remember what happened to her mother in canon, but maybe Coin took her too? And maybe Coin escaped the Capitol and the resistance with some wounds, just to put her at some sort of disadvantage. Like, maybe her injuries just make her extra nuts because she's in a weakened state and knows she can't keep hostages forever? I definitely think Coin should be our main antagonist and that she should come into play after one or two smaller conflicts, like rebuilding and recovering from everything. And starting them off in the Capitol is good with me.