Or maybe they just stay home because there’s no Republican in the race. Her supporters (what’s left of them) are probably reflex Republican voters who may lose interest. But if they do decide to vote it’s not likely they’ll pull the lever for a Dem.
But think about the 20% undecided. How many of these Independent minded voters want to vote for a third party candidate? Especially one which is explicitly Conservative. The Independents are important, and I think they will tend to drift over to Owens. With Scozzafava in the race, they were more diluted, but I see less dilution now, and I think Hoffman will get the smaller portion of them.