Despite the fact that I think it highly unlikely that Clinton can actually pull off her magic numbers-based comeback and secure the nomination, the reality is that a continued battle between her and Obama is beyond the point of arguing good vs. bad for the party.  It's bad.  Very bad.  So how can Obama 'close the deal' as Clinton put it, and at the same time go on to win the Presidency in November?  
First, the major stumbling block for Obama at the moment seems to be the Clinton camp's assertion that he can't win over blue-collar workers.  Further, a major obstacle to overcome in the general election is the Clinton hardliner holdouts who will continue to harbor their ill will towards Obama and either not turn out in the fall or (moronically) vote for McCain.
The best way for Obama to overcome both of these hurdles at the same time is to give John Edwards the VP slot.  Obviously it's presumptive to declare a VP before a candidate wins the nomination, so that's out of the question.  However, a backroom deal with Edwards guaranteeing him the VP spot in return for an immediate endorsement and active support of the Obama campaign is perfectly reasonable, and should be highly attractive to Edwards.  
The Edwards endorsement and joint ticket would accomplish two things: 1) in the primary it would immediately give Obama more support amongst both blue-collar workers and the Edwards supporters who were very disappointed their candidate lost, and 2) be a strong ticket in the General that will help make up for the Clinton hardliner losses.  
In the primary, Obama has indeed had trouble winning over blue-collar folks in those large, election-deciding states.  Edwards was the most populist candidate and with his endless repetitions of the mill-working father would immediately help give Obama some amount of cred with those voters.  Granted, it won't be enough to win that bloc over completely, but all Obama needs is enough to keep those races close enough to keep his lead in delegates and in the popular vote, and the Edwards bump would be more than enough for that.  
In the General Election, it would have even greater effect.  For one, it would help balance the ticket by improving support in the Southern states.  Second, it would give the Obama/Edwards ticket the ability to be substantially more populist in message on the economy, a subject that will almost certainly play the single largest role in determining the next President (which is also a good side-effect for those liberals who wanted a more populist candidate like Edwards, but were left with Obama and Clinton).  Third, Edwards is an experienced and tested VP candidate who performed well in the last election where he held that role (although obviously against a very detested opponent).  Last and not least, it would at least somewhat help to  win over some of those hardliner Clintonites who otherwise would abandon Obama (remember, a substantial portion of the people supporting Clinton were originally Edwards supporters, and it stands logically that at least some non-zero percentage of the hardliners were amongst that group).  
Clearly in my opinion, Obama could make no smarter move right now than to sit Edwards down and make him an offer he can't refuse.