Morris is also underestimating how much she'll suppress the male Democratic vote. I work with two hard-core Democrats, they both swear they'll stay home if she gets the nomination. They may or may not, but she's the only candidate in the field who evokes such an instantaneous, negative reaction. I think any gains she makes with single females, she loses right back with blue-collar male Democrats.
Your point about the incumbency working against is well taken. But Gingrich would have one advantage: he didn't vote for the war. Whether or not he would have is irrelevant. Hillary's going to have a difficult time playing guilty-by-association with a 10-year private citizen over a war she authorized. If the War Blame card is off the table, all we're left with is ideas. Obviously, that plays to Newt's strength.
The Rats will vote for her regardless of her vote on the war. One, they hate Republicans and see the election as another chance to repudiate the even more hated Bush. Two, she will be vehemently antiwar by that time -- already is getting there. You might be right about a significant number of Democratic men staying home or voting Republican specifically because Shrillary turns them off. But I think Democratic women, and some Republican women, who wouldn't otherwise vote for Shrillary will be propagandized by the women's magazines, Oprah, etc., into doing so.