Wouldn’t be surprised if they tried for Obama.
I think, and I think they think, Sanders, Biden, and Kaine are all losers. The DNC has one last faint hope: Obama - a long shot but might be their best shot regardless of the Constitution which they ignore anyway. Obama has gotten away with a lot of unforeseen violations of the Constitution these last seven years and he and the Left are used to passivity of the Right.
The DNC is desperate and Obama may seem like their only winning shot. Bernie, Biden, or Kaine would almost certainly lose. They might see Obama as their only real chance right now. And seven years of inaction by the states and the people of the states in the face of repeated and egregious violations of the Constitution have emboldened Obama and the Left to possibly try something like this.
As with other violations, they may try using the “dead letter” defense. Or Obama may try using martial law in some kind of invented “emergency”. Who knows? As long as they go unchallenged, the whole Constitution is up for grabs as far as the Left is concerned.
If Obama ran for a third term, who would stop him?