Detroit (CNN)Joe Biden is 76 years old. If he wins the White House in 2020, he will be 78 years old when he takes office. That would make him the oldest first-term president in American history -- eclipsing, by eight years(!), the record set by Donald Trump when he was elected in 2016 at age 70. While Biden allies insist he is totally and completely healthy, his performance -- listless and, at times, just behind the beat -- at the first debate performance added to the whispers that maybe time had caught up with the former vice president. As The...