Yes, the shiites are close to the Iranians and have the most to gain from a strong centran Iraq government since they undoubtedly form the majority. The Sunnis have the most to lose since they are the minority, and they would probably subscribe to semi-autonomous Iraqi regions so long as they would be guaranteed a share of the oil revenues.
Peter Galbraith is a competent spokesperson for the viability of a split Iraq with semi-autonomous regions comprised of the various factions and a weak central government overseeing the distribution of oil revenues, among other things. There are many websites citing Galbraith, but here is one essay clearly outlining his
plan: