Well you could slice of Anbar and let them join Syria. The Kurds and the Shia seem to be getting along fine. Slicing off Anbar would merely slice off a bunch of problem causers.
Basically we have a strong ally in Kurdistan, and we could live with a non aggressive Shia theocracy in the south.
When the Sunnis tire of fighting each other we could help 'em, as the author maintains.