On the other hand, a precedent has been set. And as anyone who has been paying any attention to American politics for the past 2 centuries will note, precedents invariably lay the groundwork for future action. Perhaps 20 years from now an Arab, or an Asian or African, will trample the American political scene and grab the election. And if anyone elects to doubt the newly-elected leader's legitimacy, then he will simply point out that it's all irrelevant; it's happened before.
Hence, we find ourselves in a catch-22, since not contesting Obama's legitimacy is hardly better than proving him illegitimate. The only thing that seems apt at this point is a complete blow up for the Democratic Party.