If you follow the author on twitter, he's also suggesting rumors with no basis whatsoever that Bloomberg or Sherrod Brown are going to jump into the race, even though his own article quotes Brown as saying he isn't. It's a clickbait article coupled with baseless tweets. Until people start voting, there's really nothing else to do but speculate. This is just noise.
There are several current candidates that are acceptable. Personally, I think the Democratic message needs to be get Trump out, repair the damage and return the government to something to something functional. Let legislators promise free college, health care, etc. The party leader needs to be focused on beating Trump. Booker keeps banging this drum, but everyone is focused on Warren and Sanders' handouts and Biden's diminishing capacity. But ultimately, I'd vote for anyone that the Democrats run out there unless someone primaries Trump.