If the Democrat establishment succeeds in blocking Bernie, many of his supporters will stay home or support a third party candidate. If Bernie is nominated, many lunch pail Democrats will consciously make the move over to Donald Trump's new Republican Party.
The rats have a dilemma.
If they stay with Joe, his sleaze will destroy him and many down ticket. Many more will fall with Joe's gaffes. Their only sensible option is to go with charisma weak Sen. Klobuchar, Gay mayor Pete or sometime Republican billionaire parachutist Bloomberg.
If I were a Democrat, my choice would be Bloomberg as the least vulnerable, least crazy, best financed, very likely to be a good loser. He would keep the party in tact and produce few gaffes. Apparently an individual of relative reason (as opposed to the certifiably crazy) Bloomberg might stop the party from disintegrating and save the House. He would, however, be anathema to Bernie's crazies.
I, too, think Bloomberg’s gigabucks are a potential wild card. If Bernie gets the nomination after suspending his campaign because of a heart attack, the VP slot becomes much more controversial than normally. On rational political calculus, Bloomberg would be the logical choice. He has positioned himself for that, at a minimum IMHO, by pledging to spend big bucks attacking Trump in any event.
Of course, there is some slight cognitive dissonance in a Bernie/Bloomberg ticket - not that that would stop Democrats.
It also has the advantage that any criticism of the Democrat ticket would automatically be “antisemitic."