Biden destroyed Ryan in the VP debate. Don’t underestimate Biden as a politician. He may be the Dems choice if Hillary is indicted or at the very least, the FBI recommends to DOJ that she be charged. The chances of that happening may be remote, but the possibility does exist. The integrity of the FBI is at stake. I have no doubt that DOJ is partisan and will not pursue the FBI findings.
Biden cannot run. The date has passed for Presidential candidates to sign up. Plus, it is too late to get his name on the early states primary ballots even if he could sign up, which he cannot.