I had composed a lengthy answer but it suddenly got swallowed up so here's a summery: Joe Biden occasionally says silly things but he isn't suffering from Dementia. I promise you.

Hillary for Veep? Her ego wouldn't allow her to accept the demotion. My prediction for Biden's running mate: Florida Congresswomen and retired Chief of the Orlando P.D. Val Demings. She's an African-American and she would be helpful in winning Florida for Biden and that would be huge.