Biden has been VP for 8 years. He would gladly take on the mantle of Obama's third term. Obana would campaign enthusiastically for Biden. He would be a far more formidable candidate than Hillary. Biden destroyed Ryan in the VP debate in 2012. The unions and minorities like Biden better than Hillary.
Maybe Kerry would be pushed by Obama to replace Hillary.
Seriously doubt it.
So far, only Trump and Cruz are creating some enthusiasm.
Trump and Sanders are the ones generating enthusiasm. No one else's crowds approach their numbers.
Some funny you tubes on Hillarys emails.
https://www.youtube.com/watch?v=Prls6Iz3B3E
https://www.youtube.com/watch?v=xs2_mqdfaJM
I have met all the candidates Dem. and Rep. Trump and Sanders had huge crowds. Hillary and Cruz had small crowds compared to the other two. You are right. Not sure someone like Biden can generate much enthusiasm unless the media scares them about losing sacred free stuff from the government. Trump has the largest crowds of all the candidates. There are more media at Trump events too.
Obama may want to campaign for someone with less negatives than Hillary. He does not want to face protestors yelling “Hillary should be in Jail.”