If you compared superdelegate counts at this point, Sanders would need to win 176% of Iowa and 290% of New Hampshire to just tie going into the southern states. (I provide the percentages, as well, we're talking Democrats, and percentages higher than 100% are not just possible, but likely...)
That's just to tie those who have already announced their support. If you add in those who are leaning, Bernie would have to win South Carolina as well with 192% of the vote. Aside from the tip of New England, his support peters out.
(I still get a kick about how an independent is in contention for the Democrat nod; man, we'd string such a creature from the rafters around here.)
Now, the real danger is if Hillary doesn't do a knock out punch to Sanders by the first week of March. Should that fail to happen, a Bloomberg or another person jumping in is likely.
But no, Hillary's future doesn't hinge on Iowa.
After two really bad losses, the aura of invincibility/inevitability is GONE..period...then everyone starts taking about Biden and Warren..