Internal Sunni pressures...

No way the Sunni Arab leadership could have ever participated in the Jan. 30 elections, even if the elections had been postponed. I think that under any electoral system, either with regional member districts, or with the closed list national PR system that ended up being implemented, the Sunnis would have boycotted, due to internal pressures. From the Feb. 10 Christian Science Monitor:

Sunnis under pressure as well

But the Sunni Arabs who the Shiite leaders are dealing with are also in a precarious position. On Monday, when members of the Islamic Clerics Committee and the Iraqi Islamic Party, another Sunni group who boycotted the election, met with Hammoudi, they rolled up in five Mercedes, behind tinted windows protecting their identities. They asked for a closed meeting. "We wanted this to be open to the public, but the Sunnis are feeling pressure from their own side," says Hammoudi, who was jailed and tortured by Hussein until his own exile. "This is a little strange - it's like we're protecting Sunnis from other Sunnis."

An aide to Hammoudi said the meeting went well, though it resulted only in an agreement to form a joint working committee to explore how Sunni demands can be met. Adnan Pachachi, a prominent secular Sunni Arab who led a list that is likely to win a few seats in the assembly, has called this week for a national reconciliation conference to ease Sunni fears.

"This is not a problem between Sunnis and Shiites," he says. "I was jailed with Sunnis from ... Tikrit," Saddam Hussein's home town. "We're not fighting Sunnis. We're fighting the old regime."

UPDATE: And Juan Cole today, in making an argument for why the insurgency may go on for years, indirectly supports my argument (which I've been mulling over, and will say more about in the future):

The old Sunni Arab power elite, mainly Baathists or the officer class, has not reconciled itself to the political ascendancy of the Shiites and Kurds. They still think they can destabilize the country and take back over. I would compare them to the Phalangists, the fascist Maronite Christians in Lebanon, who fought tooth and nail 1975-1989 against recognizing that Christians were no longer a dominant majority in Lebanon. Eventually they had to accept a 50/50 split of seats in parliament (which is generous to the Christians, given that Muslims are now a clear majority). That the Sunni Arab elite might be quicker studies than the Phalangists is possible but a little unlikely.