Elizabeth Edwards just did an interview on MSNBC and didn't sound like a woman on the verge of endorsing a candidate. (She said she didn't envision making an endorsement prior to the North Carolina primary, but didn't entirely rule it out when pressed because, she said, you never know if some change of circumstance might push you in one direction or the other.)
The interview got me thinking that the immediate benefit of the Wright press conference isn't that it puts the issue to rest, though it certainly could move us down that road. It's that it hems in high-profile people--superdelegates, wealthy donors, partisan pundits, etc.--who might otherwise have abandoned Obama on the expectation that everyone else might. Now they can't be so sure that voters will jump ship, and so they won't either.
In a nutshell, this freezes the people (i.e., political elites) who make decisions based on what they think other people think, if not the people who make decisions based on what they themselves think (i.e., most voters).
Update: Just to clarify, I'm not suggesting the superdelegates were on the verge of deserting Obama en masse. Just that we were starting to see some movement toward Hillary thanks to the feeling that Obama is more vulnerable than we'd assumed. This probably slows that momentum in the short-term, regardless of where voters end up coming down on the matter.