My only comment on Obama refusing to help Iraq, and standing by while Iran will pick up the pieces is to note the similarities of Rome in it's declining years using barbarians to fight other barbarians.
Hope this works out better.
AustinBay's cynical take is here.
StrategyPage has more: apparantly the US and Saudi are helping the Iraqis on the sly and the Kurds are coming into the fight.
The result will probably be ethnic cleansing of the Sunni minority, who are helping the terrorists, something that General Petreus stopped by getting them to switch sides during Bush's surge.
And a lot of the problem is corruption.
come to think of it, Rome's corruption is one reason the Goths turned murderous.