Apparently Erick Erickson of Red State thinks the DNC's new "Mitt vs Mitt" ad is designed to (a) sow doubts about Mitt Romney among conservative Republicans, and (b) "potentially drag out the pain of the Republican Primary before doing what every Democrat and Beltway Pundit in America thinks — settling for Romney, a guy they will have already defined as a flip-flopper."
Certainly (a) is the main point the DNC is trying to drive home, but if Democrats think that extending the primary schedule is good for them, I present the 2008 Democratic primaries as evidence for the opposition. Those primaries granted Democrats largely positive media coverage in places the otherwise never would have shown their faces: North Dakota, Indiana, North Carolina, etc. By the end of a 50-state primary season, Republicans and independents would be familiar with the arguments for and against each candidate; 11th Commandment concerns and ambitions for VP or cabinet posts would probably prevent all but the most oblique attacks in the back half of the campaign, which would otherwise go mostly uncovered.
The ideal outcome here for Democrats is probably for the anointed NotRomney to enjoy a brief, Pat Buchanan in 1996-esque moment in the sunshine, winning a couple of early primaries and then a handful of smaller states on Super Tuesday. I suppose it's possible that Gingrich could engage in some sort of Ted Kennedy-in-1980-esque "Well, things worked out a little
different from the way I thought" campaign to the bitter end, but it's not 1980 and Gingrich is savvy enough not to do that.