@hightor,
I agree with you there. The large, but still minority, cadre of enthusiastic Sanders supporters does indeed present the Democrat establishment with a serious dilemma, as the primaries progress and the Convention nears. It appears they had earlier bet that a Biden candidacy would beat Sanders in the primaries. Now, as that prospect dims, they are left with Bloomberg as the only (that I can see) option to defeat Sanders in the State Primary elections ahead. That one too has so far failed to take off, but given the resources Bloomberg is pouring into the effort, it appears too early to write him off.
The dark scenario for the DNC is a convention opening with Bernie as still the leading candidate, but with perhaps less than a majority of delegates for the first voting round in the convention. At that point the Democrat Legislative establishment that comprises most of the "super delegates" will have to make a difficult choice, with perhaps lasting consequences for their party. One prospect is the selection of Sanders as the candidate; a likely loss in the Presidential election and significant "down ballot" losses for the legislative establishment super delegates themselves. The alternative is the selection of (say) Bloomberg with, at best still uncertain, prospects in the Presidential election and the likelihood of a revolution within the party and even a possible third party movement for Sanders - something that would ensure a Trump victory.
It is interesting to consider how historians might view these events a few years from now. My view is that, in their intemperate and even irrational hatred of a very disruptive, but popular, President Trump, the Democrat leadership in the Congress has abrogated both its legislative responsibilities in addressing needed legislation with the opposing Party, and the opportunity to, in the process, develop a moderate Democrat party platform addressing real issues before the country.
Instead they have conducted endless (and sometimes illegal ) investigations, impeachment efforts based on obviously flimsy grounds, - all accompanied by expressions of hatred towards and disgust with a fairly popular president now, as a direct result of these actions, leading a very united Republican party. The Democrat Congressional Leadership has now made itself look a bit desperate and deranged in the process.
The result of this has been the continued growth and ascent of the 2016 Sanders movement, now aided by ambitious but sympathetic new far left Representatives, who, together with the Sanders supporters, have taken most of the air out of the Democrat Room. In effect the Democrat Congressional leadership has abandoned its chief responsibility in an irrational hate driven campaign against Trump, and in the process, undermined its own position, abandoning the political field to the unelectable extreme elements of the Party.