There is a lot of press these days about Joe Biden considering a run for President in 2020. One can only imagine the thoughts that run through Joe Biden's mind about what might have been in 2016 if he had actually entered the race. There is no doubt, in my mind, that there were those, potentially Obama himself, who prompted Joe to consider jumping in but I believe Joe Biden knew that it would mean crossing Hillary and that was something he wasn't man enough to do, at that time. Joe wasn't willing to get down in the ditch and campaign against Hillary in the way he would have had to in order to take the nomination away from her but even Joe Biden knew what a flawed candidate she was and that potentially he had a chance.
I don't know if he got cold feet, didn't want to go up against Hillary or was somehow cautioned against running against Hillary who I fully believe was promised the nomination and guaranteed a run to be the first female President. I halfway think Obama would have been in Joe Biden's court had Joe ran because I think Obama knew Hillary also was flawed and that Joe Biden would be his best bet at having continued effect on the Nation. Most questions we will never know unless Joe Biden talks about it, but you can still guarantee yourself that he spends countless amounts of time thinking about what could have been. Of course, that is if he would have beaten Donald Trump. I, personally believe with all the benefits and advantages that the Democrats had that he would have beaten Donald Trump. I think the Democrats lost solely due to the horrendous candidate (and person) that Hillary was and was seen to be by the vast number of voters.
As for 2020 I'm afraid that Joe's time has past and I believe enough younger candidates, potentially non-political type people, will get in the race and while Joe may have a chance at 2020 I just don't think it will happen.