Currently Online 
Some interesting article to note: https://www.politico.com/news/2019/12/02/peter-daou-clinton-aide-sanders-2020-074723
And for the fun game who holds out until when:
Staying the full primaries I can see Biden, Warren, Sanders and Buttigieg.
Candidates that hold out at least until Super Tuesday (and then may drop out based on the results) are Kamala Harris and Michael Bloomberg.
Candidates I see holding out until Iowa are John Delaney, Amy Klobuchar, Deval Patrick and Tom Steyer.
I am very uncertain about Yang and Gabbard. It is possible they hold out until Iowa, although it is also possible they drop before. I can't see them hold out the whole primary. Also a big uncertainty is Cory Booker. I don't know what his plan is at all.
Candidates I see dropping out before Iowa are Marianne Williamson and Julian Castro. Michael Bennet and Joe Sestak might also drop out before Iowa, but I am not sure why they are still in the race at all.
