The Democrats are going to suffer whether or not they pass healthcare. 1994 wasn't made any better because the Democrats failed to do anything.
I think Obama did nurture the perception that he could provide healthcare to millions of Americans without tax raises. Maybe his plan would have worked like that. But once in office all he basically did was tell congress to make a bill (because he knew that if he tried to force one on them like Clinton it would go badly).
Congress had different views on healthcare. Most Obama supporters will continue to support him anyway, and the coalition is already fractured whether or not the bill gets passed.
IMHO, this is just reason that party executives and the leadership in the legislature need to get together before the election to form a coherent plan. The executive is often elected because of his bully pulpit to force his legislative promises through, but he doesn't really have the power to do jack shit without the support of the leadership in the legislature.
all the opposition needs to do is win one senate seat to enforce their agenda of not letting bho pass anything critical to bho's agenda