Well. This match will be awesome.
However, this match shouldn't close the show. It should be 3rd from the end, followed by Batista/Cena followed by Taker/HBK. Taker/HBK will have everyone leaving happy, no matter who wins. Batista/Cena will hopefully end with Batista winning, so we need someone to win that will have a GREAT match and will keep the crowd engrossed. Jericho/Edge will be highly entertaining for us...but the average wrestling fan isn't going to be entertained by 20 minutes of technical wrestling. Even if that technical wrestling has the best story in the world (which is what I look for).
I like TM's idea of having Christian saying he will cash it in before the match. Something like before the MITB match begins we have Christian cut a promo:
"If I win the MITB match I will cash it in to have my shot against Jericho and Edge for the title."
Christian wins, and everyone says "Oooooh shit. We have a triple threat."
Think of the extra pop we would get from that. Not just "Christian won!" but "Holy shit! Triple threat! Drooooool."
Crowds love surprises, and they love surprises that come from highly contested match endings. MITB doesn't get more exciting, and a Triple Threat match for the WHC hinging on a win by Christian would have the crowd shitting themselves.
Just think HBK vs. Taker hinging on the RR, and how the crowd just sorta cried when HBK was eliminated. Multiply that by 100000 billion, and you'll have an idea.
Oh yeah, and Edge wins for his first Face title reign. Jericho goes back to square one, and loses nothing from it.