I really haven't been following this election cycle. However since yesterday's election, I have begun to read every single bit of state polling, demographic favorability polling + the exit polling of the three states for far, and little bit the punditry. I've thought through the scenarios of how each candidate could drop out and who that would hurt and help, especially relative to what's left on the map.
I cannot come up with any reasonable scenario where any other candidate has a plausible shot at the nomination. To summarize:
1.) By the end of March, >60% of delegates will be set in stone, and it looks like Bernie is leading half of the states with high single or even double digits (including Texas and California) and basically is a very close #2 in every state where he's not #1. The remaining candidates all have failed to seriously break into wider demographics. Everyone else, except maybe Biden, will come in 3, 4, or 5 more often than not. If everyone stays, this basically decreases the likelihood of any shake up.
2.) Now then, what if people drop? Well, actually, there's a good reason Klobuchar, Buttigieg, and Biden have all stayed. Most of these candidates #2 choice is Bernie, meaning that if anyone of them drop the person who'll be helped the most is likely Sanders. Given Sanders is second choice for most of them + the perception that he's the winning candidate right now, no establishment candidate can safely drop before Super Tuesday without possibly seriously helping Sanders on Super Tuesday. They just ran out the clock on their option to do this; it's simply too late to do this effectively now.
3.) And if people drop (and they will) after Super Tuesday, it basically means whoever is left will likely be fighting against Bernie --who will have a ~3 point lead in delegates, a cash surplus, he will probably have the momentum, and has the most energized base. Oh and also all current polling shows that in all 1-vs-1 situations, Bernie beats his primary contenders.
Yes, shake-ups happen, but it's looking less and less possible as the election continues.