The daily 538 cratering of Sanders continues unabated, on the verge of going sub 20% for 1991

[TwilightZone]

15. Not happening.

The math just doesn't work. Warren is forecast to get about 5% but it's unlikely she stays in until the convention. BB is forecast to get more than that, but it's highly unlikely he'll stay in the race if Biden has a good day tomorrow and has momentum. Assuming he drops out after ST or shortly thereafter, he's forecast to get about 2%. The others have a handful of delegates between them.

Assuming Warren stays in until the convention (unlikely) and that BB drops out soon (quite likely), that leaves 93%. If Sanders comes in with 48%, that means Biden has 45% (and probably more). That's not enough of a lead to just hand the nomination to Sanders.

The doomsday scenarios made in the OP and that people often make in the comments simply aren't mathematically likely. They're intentionally exaggerated to make a point, but they don't really pass muster. Sanders isn't going to be up 48/38 for the very simple fact that no one else is likely to get the other 14%.