Remember, a party convention is like the electoral college for the party. If Obama manages to get her thighness indicted a week before the convention, what are those delegates going to do? One possibility is, the party will do a bait and switch in a smoke-filled back room, appeal to party unity, and put Biden forward at the convention itself, even though he was never on a single ballot.
On the other hand Biden would get the votes of all the DC movers and shakers... every political elite would see it as a 'sure thing'... he would go down with style...