Someone would have to look into the deadlines for primaries, but I do know that Biden has missed several. If Clinton gets indicted, Sanders will rack up delegates unopposed, and the rules are that the delegates have to honor the vote on the first ballot.
If Sanders has enough votes, he will win the nomination, and there is not a thing POTUS or VPJB or the DNC or Dr. Jill Biden can do about it.
The Dems superdelegates are almost all for HRC so far. I think she gets enough votes, even with an indictment, to prevent Bernie from a first ballot win. The theory is there are enough SDs to prevent any candidate from a nomination without them.
If they (SDs) hold back support from HRC due to a legal problem, the brokering begins. I expect the indictment, or even just a statement by the AG that they received a recommendation of charges they are reviewing seriously (formal indictment not required) pretty late in the process, after she has enough support to prevent a Bernie win outright, but before the convention.
Plus, remember this theory is based on the election gymnastics for a. the Obama machine, and b. the dems. Do rules really apply?
Then they’ll just find a judge and rewrite the rules mid-game. That sort of thing has been done before.