I think everyone besides Sanders and Bloomberg need a good showing now in Nevada and/or South Carolina. Sanders seems established as a frontrunner (which also means he needs to win Nevada, or this image is damaged). Bloomberg seems established to be a strong candidate coming Super Tuesday.
Everyone else needs a strong showing before Bloomberg pushes into the race. So far Biden, Warren and Steyer had no strong showing. Steyer and Biden could possibly hope for South Carolina, as their polls are good there, but more shows of strength are obviously better. Warren cannot hope on SC, she needs a good result in Nevada.
Buttigieg and Klobuchar probably stay in the race until Super Tuesday in any case, but so far they are seen as candidates for the "white" states. A good result in Nevada or South Carolina could help a lot.
So in conclusion I see everyone hoping for the second place finish in Nevada, and the polls are close enough between all five. But only one can get it, right?
Yeah first place looks solid for Bernie, it would really hurt him to not get first. Especially if he gets second to anyone but Biden. Warren needs second the most, but only because Klobuchar isn't expected to get second anyway. Klobuchar needs a good showing though, she has to get some delegates. Same for Pete. Not getting any delegates would confirm the prevailing "Pete and Amy can't win non-whites" narrative. Under 10 percent would really hurt them, crossing that psychological "single-digits" barrier that Warren and Biden crossed in New Hampshire. Biden and Steyer still have South Carolina, so they can take a poor performance, though Biden getting single digits again would be really bad, and anything outside the top 3 would be really bad. Biden needs second the least though, because even 6th place wouldn't knock him out. He's in this to Super Tuesday no matter what.
Warren being second would breathe new life into her campaign, being non-viable would probably be a death blow. Honestly if she gets single digits in Nevada and doesn't drop out, I might start to believe Uran about her wanting to drag Sanders down out of spite. 538 already has her at less than 1% chance! Just 0.8 and still falling! She definitely needs Nevada, and getting no delegates or finishing outside the top 3 would end the campaign of any reasonable person (Note that this would mean that Gabbard is definitely not being reasonable by staying in at this point, which I also regard with suspicion). At this point, if a non-establishment candidate is still not getting delegates in most places, they're just taking percentage points from Bernie and dragging him down. You can't combine delegates at a contested convention in return for a cabinet position if you have no delegates to bargain or too few to matter.
In Warren's defense though, it's pretty ironic that in 2016 the argument against Bernie was that he and Clinton were "basically the same" because of Clinton's short Senate voting record being close to Bernie's, and that thus she's just as progressive and it's "her turn". Meanwhile now, they actually have a candidate that is much closer to Bernie than Clinton was, with a much longer record to back that up, and rhetorically similar as well. Yet rather than rally behind Warren under the same argument, the argument on one hand when they briefly supported her is that she's not like Bernie, while on the other hand they rally around various centrists just for being centrist, and bend over backwards to change the rules so a center-right billionaire can enter the race and compete, and seem to be actively seeking for a contested convention. They're not even trying for unity now. She was easily the closest thing to a unity candidate if that's what the party wanted, but they don't.