This will be quick, because the answer is rather simple. At this point, there are two choices for the Democrats, finish reform or drop it. How does this impact 2010? No one is exactly sure. The proposed plan polls poorly, although the individual provisions poll well individually. One would imagine that if the provisions themselves are popular, then reform will overall be a boost for Democratic support. Yet none of that will have taken effect by the time folks begin making decisions for 2010 elections.
So how does health care impact 2010 elections? Could go either way. There is one question I can answer: will it play better for Democrats to get reform finished or drop it all together and start over? Guaranteed, at this point in the game you have "already paid for lunch, you might as well eat it" as Chris Hayes from The Nation said.
Whether or not passage of health reform will help the 2010 elections is unclear, but failure will clearly have a strongly negative impact.