The link from The Atlantic (posted above) talks about all of the candidates and a few who had declared or might declare. What I get out of the story is a huge numbet of capable and potentially valuable candidates for Vice President. Of all likely candidates it is most likely Joe Biden or Bernie Sanders. I would love to see 2 or 3 others escalated significantly so we focus on 5 real choices and respectfully explain the reality to the bottom 15. Obviously things change and some become a more important and relevant choice when circumstances are favorable.
I hope party leadership will advise the 6 - 10 next best options that a strong 2nd name on the 2020 ticket is essential. I expect a long hard fought battle between Biden and Sanders. Both are well beyond retirement age. A strong VP is quite likely going to do far more than ribbon cutting and ceremonies. The presidency is a stressful job and the VP should be chosen with great care.