Will Barack Run -- with us?

Much as I admire the spirit of Unity08, I can't help be wonder whether we'll be overtaken by events. In particular, all four of the most prominent front-runners:

• John McCain (R)
  
• Rudy Guiliani (R)
  
• Hillary Clinton (D)
  
• Barack Obama (D)
  

are (to a greater or lesser extent) centrists, or at least pragmatists. If any of those get nominated, it seems like it will be hard to muster enthusiasm from moderates to oppose them. For examplel, Barack Obama is widely seen as representing what he describes as:

"another tradition to politics, a tradition that stretched from the days of the country’s founding to the glory of the civil rights movement, a tradition based on the simple idea that we have a stake in one another, and that what binds us together is greater than what drives us apart, and that if enough people believe in the truth of that proposition and act on it, then we might not solve every problem, but we can get something meaningful done.”

What centrist could possibly run against that?

Of course, it is entirely possible that partisan primaries may conspire against them, which means that Unity would have a ripe field to pick from. So perhaps the effort isn't in vain after all...